Pub Date : 2025-12-01Epub Date: 2025-11-10DOI: 10.1016/j.dynatmoce.2025.101612
Noreen Sher Akbar , Salman Akhtar , Shakil Shaiq , Muhammad Fiaz Hussain , Taseer Muhammad , M. Farooq , M. Bilal Habib
The advanced energy regulation systems demand an optimal heat balance that can be successfully accomplished through the application of hybrid nanofluids. This research work examines the numerical analysis on convective heat transfer with flow attributes of hybrid nanoparticles formed from molybdenum disulfide and graphene oxide inside a circular domain having narrow edge fins. We have integrated a novel fin configuration with convective heat transfer analysis of hybrid nanofluids. Thermal convection and magnetohydrodynamic effects are employed for this steady, incompressible, laminar flow phenomenon. The complex configuration of governing partial differential equations is numerically solved by utilizing finite element simulations. The impact of fin count on thermal efficiency is evaluated by incorporating 4 and 10 fins respectively. Streamlines, isotherms, and Nusselt number patterns are analyzed against significant dimensionless parameters. The increased fin count optimizes the heat transfer mechanism through improved fluid mixing and greater recirculation zones. The synergistic effects of hybrid nanofluid flow phenomenon efficiently improves heat absorption, flow characteristics, and overall thermal efficiency. The flow field is further stabilized through the application of external magnetic field effects that promotes a uniform distribution with efficient heat transfer. The fin count and design have pivotal role in supervising flow obstructions with better heat flux in magnetohydrodynamic flow environment. The increasing value of Reynold number from 1.1 to 1.5 results in a 20 % increase of Nusselt number from 3.0 to 3.6. A further increase of 11 % in Nusselt number is noted for Reynold equal to 1.7. Nusselt number significantly increases up to 67 %, 89 %, and 95 % with an 80 % increase in Prandtl number for Reynold equal to 1.1, 1.5, and 1.7 respectively. Thus, the higher flow rate and increased viscous effects significantly enhance convective heat transfer in finned tube cavity. The studied parameters have the following ranges
{"title":"Mixed convective heat transfer enhancement in hybrid nanofluid flow through complex-finned tube cavities","authors":"Noreen Sher Akbar , Salman Akhtar , Shakil Shaiq , Muhammad Fiaz Hussain , Taseer Muhammad , M. Farooq , M. Bilal Habib","doi":"10.1016/j.dynatmoce.2025.101612","DOIUrl":"10.1016/j.dynatmoce.2025.101612","url":null,"abstract":"<div><div>The advanced energy regulation systems demand an optimal heat balance that can be successfully accomplished through the application of hybrid nanofluids. This research work examines the numerical analysis on convective heat transfer with flow attributes of hybrid nanoparticles formed from molybdenum disulfide and graphene oxide inside a circular domain having narrow edge fins. We have integrated a novel fin configuration with convective heat transfer analysis of hybrid nanofluids. Thermal convection and magnetohydrodynamic effects are employed for this steady, incompressible, laminar flow phenomenon. The complex configuration of governing partial differential equations is numerically solved by utilizing finite element simulations. The impact of fin count on thermal efficiency is evaluated by incorporating 4 and 10 fins respectively. Streamlines, isotherms, and Nusselt number patterns are analyzed against significant dimensionless parameters. The increased fin count optimizes the heat transfer mechanism through improved fluid mixing and greater recirculation zones. The synergistic effects of hybrid nanofluid flow phenomenon efficiently improves heat absorption, flow characteristics, and overall thermal efficiency. The flow field is further stabilized through the application of external magnetic field effects that promotes a uniform distribution with efficient heat transfer. The fin count and design have pivotal role in supervising flow obstructions with better heat flux in magnetohydrodynamic flow environment. The increasing value of Reynold number from 1.1 to 1.5 results in a 20 % increase of Nusselt number from 3.0 to 3.6. A further increase of 11 % in Nusselt number is noted for Reynold equal to 1.7. Nusselt number significantly increases up to 67 %, 89 %, and 95 % with an 80 % increase in Prandtl number for Reynold equal to 1.1, 1.5, and 1.7 respectively. Thus, the higher flow rate and increased viscous effects significantly enhance convective heat transfer in finned tube cavity. The studied parameters have the following ranges <span><math><mrow><mn>0.1</mn><mo>≤</mo><msub><mrow><mi>P</mi></mrow><mrow><mi>r</mi></mrow></msub><mo>≤</mo><mn>20.1</mn><mi>;</mi><mn>1</mn><mo>≤</mo><mi>M</mi><mo>≤</mo><mn>41</mn><mi>;</mi><mn>0.1</mn><mo>≤</mo><msub><mrow><mi>G</mi></mrow><mrow><mi>r</mi></mrow></msub><mo>≤</mo><mn>0.002</mn><mi>;</mi><mn>1</mn><mo>≤</mo><msub><mrow><mi>R</mi></mrow><mrow><mi>e</mi></mrow></msub><mo>≤</mo><mn>31</mn><mi>;</mi><mn>1</mn><mo>≤</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>≤</mo><mn>61</mn><mi>;</mi><mn>1</mn><mo>≤</mo><msub><mrow><mi>R</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>≤</mo><mn>6</mn><mi>;</mi><mn>0.01</mn><mo>≤</mo><msub><mrow><mi>ϕ</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>≤</mo><mn>0.05</mn><mo>.</mo></mrow></math></span></div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"112 ","pages":"Article 101612"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-10-29DOI: 10.1016/j.dynatmoce.2025.101611
P. Sabu , S. Cxynna , N.N.S. Vishnu , Nirmala J. Nair , Jenson V. George , N. Anilkumar , Rahul Mohan
This study examines the mesoscale eddy variability in the Southern Subtropical Front (SSTF) and Subantarctic Front (SAF) regions of the Indian Sector of the Southern Ocean (ISSO), using high-resolution underway Conductivity-Temperature-Depth (uCTD) data collected during the 11th Indian Scientific Expedition to the Southern Ocean (February–March 2020). Two mesoscale eddies—one cyclonic (41–44 °S, ∼300 km) and one anticyclonic (45–46 °S, ∼100 km)—were identified and analyzed. These features appear to be recurring, with formation driven by baroclinic instability influenced by bathymetry. The anticyclonic eddy exhibited significant modification of local thermohaline structure through water mass mixing. Eddy-induced meridional heat transport was estimated to be ∼+ 0.075 PW north of 42 °S (northward) and ∼−0.075 PW south of 42°30′ S (southward). Notably, the Subtropical Surface Water (STSW) was advected from the SSTF to SAF via the cyclonic eddy’s periphery, resulting in regional modification of water mass between 42 °S and 45 °S. Enhanced primary productivity was observed along the cyclonic eddy's boundary, with chlorophyll-a concentrations reaching 0.8 mgm-³ . These findings highlight the dynamic role of mesoscale eddies in modulating frontal systems, cross-frontal exchange, and biological productivity, offering critical insights into the physical-biogeochemical coupling in the ISSO under a changing climate.
{"title":"Recurring eddies in the Southern Subtropical and Subantarctic Frontal regions of the Indian sector of the Southern Ocean during austral summer","authors":"P. Sabu , S. Cxynna , N.N.S. Vishnu , Nirmala J. Nair , Jenson V. George , N. Anilkumar , Rahul Mohan","doi":"10.1016/j.dynatmoce.2025.101611","DOIUrl":"10.1016/j.dynatmoce.2025.101611","url":null,"abstract":"<div><div>This study examines the mesoscale eddy variability in the Southern Subtropical Front (SSTF) and Subantarctic Front (SAF) regions of the Indian Sector of the Southern Ocean (ISSO), using high-resolution underway Conductivity-Temperature-Depth (uCTD) data collected during the 11th Indian Scientific Expedition to the Southern Ocean (February–March 2020). Two mesoscale eddies—one cyclonic (41–44 °S, ∼300 km) and one anticyclonic (45–46 °S, ∼100 km)—were identified and analyzed. These features appear to be recurring, with formation driven by baroclinic instability influenced by bathymetry. The anticyclonic eddy exhibited significant modification of local thermohaline structure through water mass mixing. Eddy-induced meridional heat transport was estimated to be ∼+ 0.075 PW north of 42 °S (northward) and ∼−0.075 PW south of 42°30′ S (southward). Notably, the Subtropical Surface Water (STSW) was advected from the SSTF to SAF via the cyclonic eddy’s periphery, resulting in regional modification of water mass between 42 °S and 45 °S. Enhanced primary productivity was observed along the cyclonic eddy's boundary, with chlorophyll-a concentrations reaching 0.8 mgm<sup>-</sup>³ . These findings highlight the dynamic role of mesoscale eddies in modulating frontal systems, cross-frontal exchange, and biological productivity, offering critical insights into the physical-biogeochemical coupling in the ISSO under a changing climate.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"112 ","pages":"Article 101611"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-11-19DOI: 10.1016/j.dynatmoce.2025.101616
S.M. Sachhin , M.S. Bharath , G.M. Sachin , U.S. Mahabaleshwar , D. Laroze , H.F. Oztop
The current research aims to examine the Joule heating and magnetic field influence on micropolar fluid flow across expanding surface, which is is significant in enhancing the efficiency in biomedical and engineering fields, In this analysis, examined the influence of entropy generation, magnetic field, porous medium, and prescribed boundary restrictions. To the best of authors knowledge, no prior research has studied all these effects simultaneously, which emphasizes the originality of the current analysis. The considered governing partial differential equations are transformed to ordinary differential equations by using similarity expressions and then formulated analytically using hypergeometric series solutions. The dual solutions have been extracted from the current analysis which offers deeper insights into the micropolar fluid behaviour under considered physical effects. The outcomes of the present analysis reveal that enhancing the porous media and magnetic field reduces the momentum by 15 %. With enhancing the internal heat source enhances the temperature by 20 %, and thermal radiation enhances temperature by 29 %, enhancing the viscosity ration reduces the velocity by 23 %. These results help in analysing the blood movement modelling, advanced medical therapies, and magnetic drug delivery among others.
{"title":"Multiple analytic solutions for irreversible mechanism and Joule heating impact on dissipative micropolar fluid flow driven by stretching/shrinking surface with PST and PHF boundary conditions","authors":"S.M. Sachhin , M.S. Bharath , G.M. Sachin , U.S. Mahabaleshwar , D. Laroze , H.F. Oztop","doi":"10.1016/j.dynatmoce.2025.101616","DOIUrl":"10.1016/j.dynatmoce.2025.101616","url":null,"abstract":"<div><div>The current research aims to examine the Joule heating and magnetic field influence on micropolar fluid flow across expanding surface, which is is significant in enhancing the efficiency in biomedical and engineering fields, In this analysis, examined the influence of entropy generation, magnetic field, porous medium, and prescribed boundary restrictions. To the best of authors knowledge, no prior research has studied all these effects simultaneously, which emphasizes the originality of the current analysis. The considered governing partial differential equations are transformed to ordinary differential equations by using similarity expressions and then formulated analytically using hypergeometric series solutions. The dual solutions have been extracted from the current analysis which offers deeper insights into the micropolar fluid behaviour under considered physical effects. The outcomes of the present analysis reveal that enhancing the porous media and magnetic field reduces the momentum by 15 %. With enhancing the internal heat source enhances the temperature by 20 %, and thermal radiation enhances temperature by 29 %, enhancing the viscosity ration reduces the velocity by 23 %. These results help in analysing the blood movement modelling, advanced medical therapies, and magnetic drug delivery among others.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"112 ","pages":"Article 101616"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145618101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-10-26DOI: 10.1016/j.dynatmoce.2025.101609
Noreen Sher Akbar , Javaria Akram , S. Ijaz , Zaib Jahan , Taseer Muhammad , Muhammad Bilal Habib , M. Fiaz Hussain , M. Farooq
The current research observes the intricate dynamics of two-dimensional Casson hybrid nanofluid flow along a propagating wavy channel. Incorporating effects owing to the induced magnetic field, the hybrid nanofluid, thermal radiation, and mixed convection in the flow of blood containing graphene oxide and the molybdenum disulfide nanoparticles, the research also focuses on determining the efficiency of the system by focusing on the factors contributing to irreversibility of the system. The impact of the induced magnetic field is incorporated through Maxwell equations, and the Casson model is adopted to depict the rheology of the blood. The no-slip conditions for velocity and temperature are observed along boundary walls. The dimensionless mathematical model is linearized under the lubrication approximation. The final set of ordinary differential equations is then solved through a robust finite element technique in which the computational domain is discretized into thousands of nodes. The obtained linear equations are then handled through the Gaussian elimination technique in Python. The iterative process was kept repeating until a convergence criterion of is achieved. The analysis of fluid flow properties for various parameters is performed through graphical results. Temperature is found to be raised by the thermal radiation parameter. Fluid flow is accelerated via a larger Casson parameter and magnetic Reynolds number. This model has a direct application in high-tech dynamism and heat management structures, such as biomedical devices and dense electronic cooling campaigns.
{"title":"High accuracy computational approach to study Casson hybrid nanofluid flow under induced magnetic field inside wavy walls configuration having peristaltic motion with entropy generation","authors":"Noreen Sher Akbar , Javaria Akram , S. Ijaz , Zaib Jahan , Taseer Muhammad , Muhammad Bilal Habib , M. Fiaz Hussain , M. Farooq","doi":"10.1016/j.dynatmoce.2025.101609","DOIUrl":"10.1016/j.dynatmoce.2025.101609","url":null,"abstract":"<div><div>The current research observes the intricate dynamics of two-dimensional Casson hybrid nanofluid flow along a propagating wavy channel. Incorporating effects owing to the induced magnetic field, the hybrid nanofluid, thermal radiation, and mixed convection in the flow of blood containing graphene oxide and the molybdenum disulfide nanoparticles, the research also focuses on determining the efficiency of the system by focusing on the factors contributing to irreversibility of the system. The impact of the induced magnetic field is incorporated through Maxwell equations, and the Casson model is adopted to depict the rheology of the blood. The no-slip conditions for velocity and temperature are observed along boundary walls. The dimensionless mathematical model is linearized under the lubrication approximation. The final set of ordinary differential equations is then solved through a robust finite element technique in which the computational domain is discretized into thousands of nodes. The obtained linear equations are then handled through the Gaussian elimination technique in Python. The iterative process was kept repeating until a convergence criterion of <span><math><mrow><mn>1</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>9</mn></mrow></msup></mrow></math></span> is achieved. The analysis of fluid flow properties for various parameters is performed through graphical results. Temperature is found to be raised by the thermal radiation parameter. Fluid flow is accelerated via a larger Casson parameter and magnetic Reynolds number. This model has a direct application in high-tech dynamism and heat management structures, such as biomedical devices and dense electronic cooling campaigns.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"112 ","pages":"Article 101609"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-11-01DOI: 10.1016/j.dynatmoce.2025.101602
Sadia Ayub , Nissren Tamam , Muyassar Norberdiyeva , Nidhal Ben Khedher
Peristaltic motion is central to biomedical flows and industrial processes, yet the combined effects of complex rheology, wall compliance, and thermal-magnetic forces remain poorly understood. This study explores the peristaltic transport of Ree–Eyring nanofluid in a curved channel under magnetic field, viscous dissipation, variable viscosity, and chemical reaction. Using long wavelength and low Reynolds number approximations, the nonlinear model is solved numerically through a shooting Runge–Kutta scheme. Results demonstrate that variable viscosity parameter positively impact the velocity and temperature while negatively impacting the concentration profile of nanoparticles in lower channel. The findings provide physical insights into heat and mass transfer in non-Newtonian nanofluids, with direct applications in biomedical device design, polymer processing, and energy systems.
{"title":"Numerical simulation for peristaltic activity of Ree–Eyring nanofluid in curved configuration","authors":"Sadia Ayub , Nissren Tamam , Muyassar Norberdiyeva , Nidhal Ben Khedher","doi":"10.1016/j.dynatmoce.2025.101602","DOIUrl":"10.1016/j.dynatmoce.2025.101602","url":null,"abstract":"<div><div>Peristaltic motion is central to biomedical flows and industrial processes, yet the combined effects of complex rheology, wall compliance, and thermal-magnetic forces remain poorly understood. This study explores the peristaltic transport of Ree–Eyring nanofluid in a curved channel under magnetic field, viscous dissipation, variable viscosity, and chemical reaction. Using long wavelength and low Reynolds number approximations, the nonlinear model is solved numerically through a shooting Runge–Kutta scheme. Results demonstrate that variable viscosity parameter positively impact the velocity and temperature while negatively impacting the concentration profile of nanoparticles in lower channel. The findings provide physical insights into heat and mass transfer in non-Newtonian nanofluids, with direct applications in biomedical device design, polymer processing, and energy systems.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"112 ","pages":"Article 101602"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-10-25DOI: 10.1016/j.dynatmoce.2025.101610
Xianqi Zhang , He Ren , Jiawen Liu , Yang Yang , Yike Liu
Global climate change and the increasing frequency of extreme weather events are exacerbating environmental degradation and water resource challenges. Given the complexity of reservoirs, it is important to assess the impact on reservoir water quality enhancement through testing. In this study, the hydrodynamic-water quality module coupling was constructed with the help of MIKE21 software and applied to Miyun Reservoir, and the improved water quality enhancement was subsequently validated and three different scenarios were evaluated for water quality. The results showed a significant improvement in water quality in the reservoirs with an average improvement rate of 38.65 %, and pollutant concentrations diffused towards the center of the reservoir in a gradient. The water quality is best improved when the flow rate was doubled and the duration of recharge was reduced by 50 %. In conclusion, the water quality enhancement effect of this study is of great significance for other reservoirs to improve water quality and protect the ecosystem.
{"title":"MIKE21-based reservoir water quality enhancement simulation study: The case of Miyun Reservoir, China","authors":"Xianqi Zhang , He Ren , Jiawen Liu , Yang Yang , Yike Liu","doi":"10.1016/j.dynatmoce.2025.101610","DOIUrl":"10.1016/j.dynatmoce.2025.101610","url":null,"abstract":"<div><div>Global climate change and the increasing frequency of extreme weather events are exacerbating environmental degradation and water resource challenges. Given the complexity of reservoirs, it is important to assess the impact on reservoir water quality enhancement through testing. In this study, the hydrodynamic-water quality module coupling was constructed with the help of MIKE21 software and applied to Miyun Reservoir, and the improved water quality enhancement was subsequently validated and three different scenarios were evaluated for water quality. The results showed a significant improvement in water quality in the reservoirs with an average improvement rate of 38.65 %, and pollutant concentrations diffused towards the center of the reservoir in a gradient. The water quality is best improved when the flow rate was doubled and the duration of recharge was reduced by 50 %. In conclusion, the water quality enhancement effect of this study is of great significance for other reservoirs to improve water quality and protect the ecosystem.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"112 ","pages":"Article 101610"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-10-18DOI: 10.1016/j.dynatmoce.2025.101606
Kuiping Li , Keyi Wang
The quasi-biweekly oscillation (QBWO) represents a significant sub-seasonal variability in the tropical atmosphere, exerting profound impacts on weather and climate systems across the northwestern Pacific. This study investigates the distinct initiation mechanisms of QBWO convection during boreal summers (June-July-August-September) under El Niño and La Niña developing conditions. In La Niña summers, the initiation of QBWO convection is characterized by weaker activity and shallow convection in the initiation region (150°-170°E, 5°S-5°N), which is preconditioned by westward-moving moisture precursors. Subsequently, QBWO convection travels westward along the equator before eventually evolves into deep convection and triggers a distinct forced equatorial Rossby wave response. In contrast, during El Niño summers, QBWO convection initiates more vigorously, manifesting as deep convection right from the onset. A notable Rossby wave response is observed as convection develops, but unlike in La Niña years, the initiation is not preceded by a precursory moisture signal. Instead, it is triggered by a baroclinic divergence field at the equator, which is intricately linked to the meridional winds associated with double unstable developing Rossby wave cells in both hemispheres. These marked disparities in QBWO convection initiation between La Niña and El Niño years are likely attributable to ENSO-induced interannual variations in atmospheric circulation, particularly concerning vertical wind shear and moisture availability. Our findings not only advance the understanding of QBWO initiation dynamics but also shed light on its interannual modulation, thereby offering potential improvements for sub-seasonal climate predictability in tropical regions.
{"title":"Initiation of quasi-biweekly oscillation over the equatorial western pacific during El Niño and La Niña developing summers","authors":"Kuiping Li , Keyi Wang","doi":"10.1016/j.dynatmoce.2025.101606","DOIUrl":"10.1016/j.dynatmoce.2025.101606","url":null,"abstract":"<div><div>The quasi-biweekly oscillation (QBWO) represents a significant sub-seasonal variability in the tropical atmosphere, exerting profound impacts on weather and climate systems across the northwestern Pacific. This study investigates the distinct initiation mechanisms of QBWO convection during boreal summers (June-July-August-September) under El Niño and La Niña developing conditions. In La Niña summers, the initiation of QBWO convection is characterized by weaker activity and shallow convection in the initiation region (150°-170°E, 5°S-5°N), which is preconditioned by westward-moving moisture precursors. Subsequently, QBWO convection travels westward along the equator before eventually evolves into deep convection and triggers a distinct forced equatorial Rossby wave response. In contrast, during El Niño summers, QBWO convection initiates more vigorously, manifesting as deep convection right from the onset. A notable Rossby wave response is observed as convection develops, but unlike in La Niña years, the initiation is not preceded by a precursory moisture signal. Instead, it is triggered by a baroclinic divergence field at the equator, which is intricately linked to the meridional winds associated with double unstable developing Rossby wave cells in both hemispheres. These marked disparities in QBWO convection initiation between La Niña and El Niño years are likely attributable to ENSO-induced interannual variations in atmospheric circulation, particularly concerning vertical wind shear and moisture availability. Our findings not only advance the understanding of QBWO initiation dynamics but also shed light on its interannual modulation, thereby offering potential improvements for sub-seasonal climate predictability in tropical regions.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"112 ","pages":"Article 101606"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145362472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-11-10DOI: 10.1016/j.dynatmoce.2025.101614
T. Salahuddin , A. Maqsood , Muhammad Awais , Mair Khan , Anum Tanveer , Samia Elattar
In this study, we analyse the boundary layer flow and heat transport of a two-dimensional Cross fluid model flowing over a linearly stretched sheet. The variable thermal conductivity, mass diffusivity, chemical interactions, and viscous dissipation are also used to depict intricate transport processes. To simulate realistic stratified boundary layers, double stratification is included in both the temperature and concentration fields. By using the boundary layer approximation approach, the governing partial differential equations are obtained. The transformed ordinary differential equations are calculated by using the suitable transformations. The modelled problem is graphically handled using numerical techniques (BVP4c) in MATLAB software. Graphical representations of important factors on concentration, velocity and temperature fields are illustrated. The findings show that when the thermal stratification parameter is increased, then the wall temperature declines. For the same range of variance, solutal stratification also reduces surface concentration. The power law index and Weissenberg number reduce the velocity of fluid. The Eckert number, which measures viscous dissipation, greatly increases fluid heating and thickens the thermal boundary layer. The higher inputs of chemical reaction lower the concentration region. The variable thermal conductivity enhances the temperature region, and variable mass diffusion augments the concentration profile. The arrangement of the boundary layer is significantly influenced by the combined impacts of stratification, dissipation, and varied transport characteristics.
{"title":"Double-layer stratification of Cross fluid flow with viscous dissipation and variable thermal conductivity","authors":"T. Salahuddin , A. Maqsood , Muhammad Awais , Mair Khan , Anum Tanveer , Samia Elattar","doi":"10.1016/j.dynatmoce.2025.101614","DOIUrl":"10.1016/j.dynatmoce.2025.101614","url":null,"abstract":"<div><div>In this study, we analyse the boundary layer flow and heat transport of a two-dimensional Cross fluid model flowing over a linearly stretched sheet. The variable thermal conductivity, mass diffusivity, chemical interactions, and viscous dissipation are also used to depict intricate transport processes. To simulate realistic stratified boundary layers, double stratification is included in both the temperature and concentration fields. By using the boundary layer approximation approach, the governing partial differential equations are obtained. The transformed ordinary differential equations are calculated by using the suitable transformations. The modelled problem is graphically handled using numerical techniques (BVP4c) in MATLAB software. Graphical representations of important factors on concentration, velocity and temperature fields are illustrated. The findings show that when the thermal stratification parameter is increased, then the wall temperature declines. For the same range of variance, solutal stratification also reduces surface concentration. The power law index and Weissenberg number reduce the velocity of fluid. The Eckert number, which measures viscous dissipation, greatly increases fluid heating and thickens the thermal boundary layer. The higher inputs of chemical reaction lower the concentration region. The variable thermal conductivity enhances the temperature region, and variable mass diffusion augments the concentration profile. The arrangement of the boundary layer is significantly influenced by the combined impacts of stratification, dissipation, and varied transport characteristics.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"112 ","pages":"Article 101614"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-11-06DOI: 10.1016/j.dynatmoce.2025.101607
Mazhar Hussain , Sadia Hameed , Noreen Sher Akbar , Taseer Muhammad
<div><div>The unsteady squeezing flow of a hybrid nanofluid made up of water-suspended zinc <span><math><mrow><mo>(</mo><mi>Zn</mi><mo>)</mo></mrow></math></span> and titanium dioxide <span><math><mrow><mo>(</mo><mi>Ti</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></mrow></math></span> nanoparticles trapped between two infinitely parallel plates is examined in this work. The need for advanced thermal management in applications where traditional fluids have poor thermal conductivity, like lubrication devices, cooling units, propulsion systems, and microelectronics, is what drives the issue. To simulate realistic operating conditions, the model incorporates radiative heat transfer, mixed convection, time-dependent magnetic field, and heat absorption. The governing partial differential equations of mass, momentum, and energy are transformed into coupled nonlinear ordinary differential equations using similarity transformations and solved numerically with MATLAB’s <strong>bvp4c</strong> solver. Results show that increasing the unsteadiness squeezing parameter accelerates the fluid motion and enhances convective heat transfer, reducing the temperature profile by up to 18 % compared with the baseline case. Suction reduces boundary layer thickness and increases heat transfer rate, while injection has the opposite effect. Stretching initially accelerates fluid motion but is eventually counteracted by viscous damping, squeezing, and Lorentz forces. Mixed convection enhances velocity by up to 12 % before destabilizing the flow at higher values. Radiation and heat absorption parameters significantly raise the temperature profile, with heat absorption increasing thermal energy near the plates by about 15 %. The novelty of this work lies in combining a time-dependent magnetic field, radiative transfer, heat absorption, and squeezing flow for the <span><math><mrow><mo>(</mo><mi>Ti</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>−</mo><mi>Zn</mi><mo>/</mo><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>O</mi><mo>)</mo></mrow></math></span> hybrid nanofluid, which has not been previously addressed. These findings provide quantitative insights into optimizing hybrid nanofluid-based cooling technologies for engineering applications.</div><div>Quantitatively, the results reveal that the velocity of the <span><math><mrow><mo>(</mo><mi>Zn</mi><mi>–</mi><mi>Ti</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>/</mo><mspace></mspace><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>O</mi><mo>)</mo></mrow></math></span> hybrid nanofluid decreases by up to <strong>14 %</strong> with increasing magnetic parameter, while the unsteadiness parameter enhances velocity by nearly <strong>11 %</strong>. Heat transfer is found to increase by about <strong>17 %</strong> under suction and by nearly <strong>19 %</strong> with stronger thermal radiation, whereas heat absorption reduces the Nuss
{"title":"Computational study of thermal effects on squeezing flow of water based (TiO2−Zn) hybrid nanofluid in a parallel plates for microelectronics dispersal","authors":"Mazhar Hussain , Sadia Hameed , Noreen Sher Akbar , Taseer Muhammad","doi":"10.1016/j.dynatmoce.2025.101607","DOIUrl":"10.1016/j.dynatmoce.2025.101607","url":null,"abstract":"<div><div>The unsteady squeezing flow of a hybrid nanofluid made up of water-suspended zinc <span><math><mrow><mo>(</mo><mi>Zn</mi><mo>)</mo></mrow></math></span> and titanium dioxide <span><math><mrow><mo>(</mo><mi>Ti</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></mrow></math></span> nanoparticles trapped between two infinitely parallel plates is examined in this work. The need for advanced thermal management in applications where traditional fluids have poor thermal conductivity, like lubrication devices, cooling units, propulsion systems, and microelectronics, is what drives the issue. To simulate realistic operating conditions, the model incorporates radiative heat transfer, mixed convection, time-dependent magnetic field, and heat absorption. The governing partial differential equations of mass, momentum, and energy are transformed into coupled nonlinear ordinary differential equations using similarity transformations and solved numerically with MATLAB’s <strong>bvp4c</strong> solver. Results show that increasing the unsteadiness squeezing parameter accelerates the fluid motion and enhances convective heat transfer, reducing the temperature profile by up to 18 % compared with the baseline case. Suction reduces boundary layer thickness and increases heat transfer rate, while injection has the opposite effect. Stretching initially accelerates fluid motion but is eventually counteracted by viscous damping, squeezing, and Lorentz forces. Mixed convection enhances velocity by up to 12 % before destabilizing the flow at higher values. Radiation and heat absorption parameters significantly raise the temperature profile, with heat absorption increasing thermal energy near the plates by about 15 %. The novelty of this work lies in combining a time-dependent magnetic field, radiative transfer, heat absorption, and squeezing flow for the <span><math><mrow><mo>(</mo><mi>Ti</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>−</mo><mi>Zn</mi><mo>/</mo><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>O</mi><mo>)</mo></mrow></math></span> hybrid nanofluid, which has not been previously addressed. These findings provide quantitative insights into optimizing hybrid nanofluid-based cooling technologies for engineering applications.</div><div>Quantitatively, the results reveal that the velocity of the <span><math><mrow><mo>(</mo><mi>Zn</mi><mi>–</mi><mi>Ti</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>/</mo><mspace></mspace><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>O</mi><mo>)</mo></mrow></math></span> hybrid nanofluid decreases by up to <strong>14 %</strong> with increasing magnetic parameter, while the unsteadiness parameter enhances velocity by nearly <strong>11 %</strong>. Heat transfer is found to increase by about <strong>17 %</strong> under suction and by nearly <strong>19 %</strong> with stronger thermal radiation, whereas heat absorption reduces the Nuss","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"112 ","pages":"Article 101607"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-09-13DOI: 10.1016/j.dynatmoce.2025.101599
Mubbashar Nazeer , Ali B.M. Ali , Farooq Hussain , N. Beemkumar , Khayrilla Kurbonov , Vatsal Jain , M. Ijaz Khan , Nidhal Ben Khedher
Objective
The aim of this study is to analyze the momentum and heat transfer characteristics within a porous medium influenced by thermal radiation, slip boundary conditions, and temperature-dependent viscosity and thermal conductivity.
Problem statement
The Poiseuille flow of MHD Jeffrey fluid through the horizontal infinite slippery walls filled by porous medium is discussed in this theoretical analysis under the contribution of variably viscosity and thermal conductivity along viscous dissipation and thermal radiation effects.
Methodology
The problem is simplified into ordinary differential equations through the dimensionless numbers and parameters. The resultant boundary values problem is solved by using the numerical technique (shooting method based on Runge-Kutta method) to regulate the velocity and temperature profiles. The graphs of velocity and temperature are drawn against the dimensionless parameters and numbers under the acceptable range.
Outcomes
The outcome of the study reveals that the temperature dependent viscosity improves the flow phenomena and thermal profile, but variable thermal conductivity declines the profile of temperature. The velocity slip upgrades the velocity distribution and thermal sip enhances the temperature field. The velocity and thermal profile of Jeffrey fluid is superior to the Newtonian fluid under the impact of each dimensionless parameter and numbers.
Applications
The results offer valuable insights for applications that demand effective thermal regulation and accurate fluid flow control, enhancing their relevance to both engineering and biomedical fields.
Originality/value
Earlier research has not presented a comparative investigation of Newtonian and non-Newtonian fluid flows through porous media, considering the combined influences of a uniform magnetic field, thermal radiation, slip boundary conditions, and temperature-dependent viscosity and thermal conductivity. This study is undertaken to address this identified gap in literature.
{"title":"Poiseuille flow of Jeffrey fluid with variable transport properties in porous media under magnetic and radiative effects","authors":"Mubbashar Nazeer , Ali B.M. Ali , Farooq Hussain , N. Beemkumar , Khayrilla Kurbonov , Vatsal Jain , M. Ijaz Khan , Nidhal Ben Khedher","doi":"10.1016/j.dynatmoce.2025.101599","DOIUrl":"10.1016/j.dynatmoce.2025.101599","url":null,"abstract":"<div><h3>Objective</h3><div>The aim of this study is to analyze the momentum and heat transfer characteristics within a porous medium influenced by thermal radiation, slip boundary conditions, and temperature-dependent viscosity and thermal conductivity.</div></div><div><h3>Problem statement</h3><div>The Poiseuille flow of MHD Jeffrey fluid through the horizontal infinite slippery walls filled by porous medium is discussed in this theoretical analysis under the contribution of variably viscosity and thermal conductivity along viscous dissipation and thermal radiation effects.</div></div><div><h3>Methodology</h3><div>The problem is simplified into ordinary differential equations through the dimensionless numbers and parameters. The resultant boundary values problem is solved by using the numerical technique (shooting method based on Runge-Kutta method) to regulate the velocity and temperature profiles. The graphs of velocity and temperature are drawn against the dimensionless parameters and numbers under the acceptable range.</div></div><div><h3>Outcomes</h3><div>The outcome of the study reveals that the temperature dependent viscosity improves the flow phenomena and thermal profile, but variable thermal conductivity declines the profile of temperature. The velocity slip upgrades the velocity distribution and thermal sip enhances the temperature field. The velocity and thermal profile of Jeffrey fluid is superior to the Newtonian fluid under the impact of each dimensionless parameter and numbers.</div></div><div><h3>Applications</h3><div>The results offer valuable insights for applications that demand effective thermal regulation and accurate fluid flow control, enhancing their relevance to both engineering and biomedical fields.</div></div><div><h3>Originality/value</h3><div>Earlier research has not presented a comparative investigation of Newtonian and non-Newtonian fluid flows through porous media, considering the combined influences of a uniform magnetic field, thermal radiation, slip boundary conditions, and temperature-dependent viscosity and thermal conductivity. This study is undertaken to address this identified gap in literature.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"112 ","pages":"Article 101599"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145097761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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