International Journal of Thermofluids最新文献

{"title":"Casson fluid flow dynamics between parallel discs: A neural network-based computational approach","authors":"Talha Anwar ,&nbsp;Mehreen Fiza ,&nbsp;Kashif Ullah ,&nbsp;Hakeem Ullah ,&nbsp;Seham M. Al-Mekhlafi","doi":"10.1016/j.ijft.2025.101468","DOIUrl":"10.1016/j.ijft.2025.101468","url":null,"abstract":"<div><h3>Significance</h3><div>Casson fluid flow between parallel discs has significant applications in biomedical devices such as blood pumps, dialysis units, and artificial valves, in industrial processes involving inks, paints, and food pastes, and in engineering systems including lubrication, cooling and polymer processing. Artificial Neural Networks are increasingly applied in fluid dynamics for their ability to approximate nonlinear systems, reduce computational cost, and provide accurate predictions compared to traditional numerical schemes.</div></div><div><h3>Purpose</h3><div>This work proposes a supervised learning approach using Artificial Neural Network Backpropagation trained with the Levenberg-Marquardt scheme (ANN-BLMS) to obtain numerical solutions of Casson fluid flow between two parallel discs with dissimilar in-plane motion (CFFPD). The method improves accuracy and stability, reduces computational cost, and predicts fluid flow behavior under varying physical parameters, with emphasis on the effects of the rotation parameter, Reynolds number, and Casson parameter on velocity profiles.</div></div><div><h3>Methodology</h3><div>The system of governing partial differential equations is converted into dimensionless ordinary differential equations through similarity transformation and solved using the ANN-BLMS. The data for this study were obtained using NDSolve method and subsequently optimized with an artificial neural network. The data set for ANN-BLMS is computed by using 15% of the data for testing (TT), 15%for the training (TR), and 75% of the data, selected randomly, for validation (VL). Error histograms (EH) and regression (RG) measurements, together with strong agreement with known solutions, demonstrate the dependability of the developed algorithms, ANN-BLMS, on CFFPD, with an accuracy range from 10⁻³to 10⁻⁷.</div></div><div><h3>Findings</h3><div>The radial velocity increases with the Casson parameter in the range 0 &lt; η &lt; 0.5, but decreases for 0.5 ≤ η ≤ 1, while the azimuthal velocity decreases for the Casson parameter grows. For both Reynolds number, and rotation parameter the radial velocity declines when 0 &lt; η &lt; 0.5, and rises for 0.5 ≤ η ≤ 1. The azimuthal velocity increases with the increase in both the Reynolds number and rotation parameter. The ANN-BLMS approach demonstrates strong agreement with existing solutions, offering higher accuracy, stability, and lower computational cost compared to traditional numerical methods.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101468"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145568798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal and mechanical characteristics of natural fiber-reinforced composites using bio-binder as sustainable insulation materials","authors":"Amged ElHassan ,&nbsp;Basim Abu-Jdayil ,&nbsp;Waleed Ahmed","doi":"10.1016/j.ijft.2025.101507","DOIUrl":"10.1016/j.ijft.2025.101507","url":null,"abstract":"<div><div>To reduce deforestation and promote the utilization of agro-industrial by-products this study fabricated a completely bio-derived composite using date trunk fibers and non-edible okra as sustainable feedstock. Composites with 0–50 wt. percentage okra content were produced using compression molding and tested to assess mechanical strength, thermal insulation, and sound absorption. Rising okra proportion improved interfacial bonding and minimized porosity, leading to increased compressive strength (up to 28 MPa) and elastic modulus (0.49 GPa). Thermal conductivity numbers were observed in the range between 0.051and 0.067 W/m.K at room temperature, confirming suitability for insulation applications. The fabricated composites demonstrated high thermal stability with 11 % mass loss at 270 °C, and achieving a maximum acoustic absorption coefficient (0.9). The specific heat capacity values were found between 1.35 × 10³ and 2.38 × 10³ J/kg·K, and corresponding thermal diffusivity between 0.0307 and 0.0651 mm²/s, reflecting effective heat storage. These results validate the use of date palm and okra by-products as feedstock for bio-based composites fabrication via a simple method without depending on any toxic ingredients, pretreatment, and sophisticated processing. These results confirm that valorizing date palm trunk fibers and okra residues into bio-based composites, and acoustically efficient materials for construction use in arid climates.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101507"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145568803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermo-magnetic stratified flow capturing Soret-Dufour impacts in rate type reactive material under varying liquid aspects and stratifications","authors":"F. Shahzad ,&nbsp;Ali B.M. Ali ,&nbsp;M. Waqas ,&nbsp;Gaganjot Kaur ,&nbsp;Ramneek Sidhu ,&nbsp;Tadesse Walelign ,&nbsp;Umid Turdialiyev ,&nbsp;Nidhal Ben Khedher","doi":"10.1016/j.ijft.2025.101479","DOIUrl":"10.1016/j.ijft.2025.101479","url":null,"abstract":"<div><div>In various industrial frameworks encompassing biofluids, polymers and coatings, interpreting viscoelastic characteristics is indispensable for accomplishing regulated mass and heat transmission. The viscoelastic Oldroyd-B material efficiently characterizes such type of materials where reaction kinetics, concentration and temperature fluctuate at the same time. The current analysis considers the magnetically driven viscoelastic Oldroyd-B material over a magnetized moving surface subjected to variable thermal and variable mass features. The Lorentzian force is introduced due to magnetic field consideration while variable thermosolutal conditions are opted because of dual stratification aspects. In addition, mass transmission features chemical reaction effects. Apposite similarity variables are introduced to transfigure governing PDEs (partial differential equations) into nonlinear ODEs (ordinary differential equations) which are computed analytically through homotopy analysis scheme. A comparative assessment with available published outcomes authenticates the accurateness of analytical outcomes. Besides, the outcomes disclose that Hartman number considerably impact the velocity distribution while solutal and thermal fields are strongly affected via varying conductivity and varying diffusivity factors. These outcomes offer indispensable perception into diffusive-thermo control in coating flows.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101479"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A review of industrial pumps for viscous and non-Newtonian slurry transport","authors":"Oscar Ifidon ,&nbsp;Daya Shankar Pandey ,&nbsp;Khurshid Ahmad ,&nbsp;Artur J. Jaworski ,&nbsp;Faisal Asfand","doi":"10.1016/j.ijft.2025.101450","DOIUrl":"10.1016/j.ijft.2025.101450","url":null,"abstract":"<div><div>This paper presents a concise review of industrial pumps for viscous and non-Newtonian slurry transport. It combines both the computational fluid dynamics (CFD) and experimental analysis to investigate the performance and limitations of various rotodynamic and positive displacement (PD) pumps for various slurry transport applications. The factors influencing head, efficiency and reliability in rotodynamic and PD pumps were evaluated for viscous and non-Newtonian fluids applications. Available literature showed that centrifugal pumps experience head losses of ≥ 8 m and efficiency reduction of 20 % when viscosity approaches 800–1000 cP, whereas the blade and volute optimisation could improve the overall efficiency. The performance of the multiphase pump showed a sharp decline when handling non-Newtonian fluids, primarily due to the formation of complex vortex structures and tip‑leakages. This study also highlighted key geometric parameters for optimisation to improve overall performance and enable the integration of multiphase pumps as a prime mover in a jet pump system, for a robust handling of highly viscous and solid‑laden fluids. While the special‑effect jet pumps had lower peak efficiencies compared to other rotodynamic pumps, robustness and passability for abrasive and multiphase flows were demonstrated, achieving up to 40 % efficiency in sand slurry applications. PD pumps, such as the reciprocating plunger and diaphragm designs, exhibited the highest viscosity tolerance, however, their performance was limited by valve response and mechanical complexity. This review particularly focused on the capabilities of Tesla disc pump for handling highly viscous and abrasive fluids. Literature on Tesla disc pumps emphasised that geometric optimisation of the disc impeller, combined with the use of a dedicated volute, could significantly enhance its efficiency and position it as a complementary solution to both centrifugal and PD pumps. The analysis of life cycle cost (LCC) showed that the Tesla disc pump maintained moderate costs for harsh applications, indicating a sustainable operational life cycle.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101450"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Supervised machine learning approach to estimating the convective heat transfer coefficient for heated oblate spheroidal particles","authors":"Belal Al-Zaitone,&nbsp;Tariq Ammar,&nbsp;Al Husain Sami,&nbsp;Mohamed Elshabrawy,&nbsp;Mohamad Kozal","doi":"10.1016/j.ijft.2025.101476","DOIUrl":"10.1016/j.ijft.2025.101476","url":null,"abstract":"<div><div>An accurate prediction of the convective heat transfer coefficient for heated non-spherical particles is important in many engineering applications. In this work, a supervised machine learning (ML)-based model is proposed to predict the Nusselt number (Nu) of heated oblate spheroidal particles in laminar flow. A computational fluid dynamics (CFD) dataset of Nusselt numbers is obtained from COMSOL Multiphysics simulations performed at different Reynolds numbers, aspect ratios, and surface temperatures. Three supervised ML models are trained and compared — gradient boosting regressor (GBR), random forest (RF), and ridge regression — and cross-validation and model evaluation are performed using standard performance metrics (R² and RMSE). Among the three models, the GBR model achieves the best predictive performance by capturing the nonlinear joint associations of geometric and thermal factors. Hyperparameter optimization is implemented to improve model performance. An accurate predictive model is suggested as an alternative to classical empirical correlations to estimate Nu for oblate spheroids, establishing a theoretical and data-driven foundation relevant to industrial processes like gas-solid reactions, aerosols, and fluidized beds.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101476"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145520092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magneto-thermal analysis of tri-hybrid blood-based nanofluid flow at a stagnation point over a stretching cylinder under Joule heating","authors":"S. Baskaran ,&nbsp;K. Senthilvadivu ,&nbsp;K. Chellapriya ,&nbsp;K. Loganathan ,&nbsp;Saleem Nasir ,&nbsp;Abdallah Berrouk ,&nbsp;R. Sowrirajan","doi":"10.1016/j.ijft.2025.101506","DOIUrl":"10.1016/j.ijft.2025.101506","url":null,"abstract":"<div><div>This study investigates the flow and heat transfer behavior of a ternary hybrid nanofluid composed of gold (Au), silicon dioxide <span><math><mrow><mo>(</mo><msub><mrow><mi>SiO</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></mrow></math></span>, and titanium dioxide <span><math><mrow><mo>(</mo><msub><mrow><mi>TiO</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></mrow></math></span> nanoparticles dispersed in blood, representing a biologically relevant medium for biomedical applications such as targeted drug delivery, hyperthermia therapy, and diagnostic imaging. The research focuses on stagnation-point flow over a cylindrically stretching surface, simulating arterial flow subjected to external thermal and magnetic effects. The fundamental partial differential formulations were systematically reduced to a set of coupled ordinary differential equations through the application of appropriate transformations, numerically tackled via MATLAB’s bvp4c solver. The validation of the numerical approach against benchmark studies confirmed the accuracy of the results. Key findings reveal that increasing magnetic field strength and porosity parameter suppressed the velocity profile. Elevated Eckert number broadened the thermal boundary layer thickness. Nanofluid concentration levels improved with stronger thermophoretic activity, while larger Lewis number diminished nanoparticle concentration. Wall shear stress exhibited a downward trend under intensified magnetic and porous conditions. Furthermore, heat transfer weakened in response to Eckert number, magnetic effects and Brownian motion, yet was augmented by the Biot number. Enhanced Lewis number contributed to an increase in mass transfer rate. These results highlight the effectiveness of tri-hybrid nanofluids in improving thermal and mass transfer performance in biologically relevant flows and provide essential guidance for the design of advanced biomedical devices and thermal management systems.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101506"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145568799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Applicable temperature prediction of composite heat exchanger group in construction vehicle by area-weighted modified ɛ-Ntu model","authors":"Yunjia Liang ,&nbsp;Jiaxin Liu ,&nbsp;Naijiang Liu ,&nbsp;Shikui Jia ,&nbsp;Tianci Zhang ,&nbsp;Martin Krechel","doi":"10.1016/j.ijft.2025.101498","DOIUrl":"10.1016/j.ijft.2025.101498","url":null,"abstract":"<div><div>To address the harsh and variable conditions in recent years, an increasing number of construction vehicles have adopted composite heat exchanger systems. The common recognized performance prediction on a single heat exchanger might be still behind the composite heat exchanger group for its complexity. In this paper, an area-weighted model was proposed for the applicable ambient temperature prediction of the heat exchanger system based on the modified <em>ε-Ntu</em> method involving j and f factors of each heat exchanger in the system. Firstly, an overview of the architecture of a composite “3 + 1″ heat exchanger system were in the first row side by side and a size-matching coolant heat exchanger was placed in the rear row along the airflow direction, was presented, together with the corresponding heat transfer principle for this system. Then, the detailed prediction on the heat transfer quantity of the system was introduced based on the modified <em>ε-Ntu</em> method. Following that, a field experiment was conducted to validate the model correctness to the further prediction. At last, the prediction on the temperature was performed for the stableness of the current system. It is found that the predicted heat transfer quantities of four different heat exchangers, 37,687.24 W, 30,450.47 W, 3660.15 W, and 86,541.42 W under 16 °C, could secure the model duty with the maximum 5.10 % error. The applicable ambient temperature is 34 °C with a 3696.57-W coolant heat exchanger. This paper is expected to provide a scientific basis for the performance evaluation of composite heat exchanger systems for construction vehicles.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101498"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145568800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conjugate CFD modeling for Multi-Sample drying of deformable porous food materials","authors":"Mohammad U.H. Joardder ,&nbsp;Abdul Mojid Parvej ,&nbsp;Md. BakhtierKhalzi ,&nbsp;Azharul Karim","doi":"10.1016/j.ijft.2025.101449","DOIUrl":"10.1016/j.ijft.2025.101449","url":null,"abstract":"<div><div>Drying of deformable porous materials (DPMs) involves complex coupling of heat transfer, moisture migration, and structural deformation, which are often oversimplified in conventional models. This study introduces a novel CFD-integrated conjugate model for hot air drying of multiple deformable food samples, capturing real-time changes in air properties and sample interactions. A key innovation lies in the investigation of drying kinetics and temperature distribution under two deformation approaches: (i) uniform deformation using a constant shrinkage velocity, and (ii) non-uniform deformation based on transport properties and the glass transition concept. The model reveals that deformation significantly alters drying kinetics by increasing surface area-to-volume ratio (SAVR), reducing internal resistance, and enhancing heat transfer from surface to center. These effects accelerate moisture migration and improve drying efficiency. Additionally, variations in drying conditions such as air velocity, temperature, and sample arrangement further influence the heat and mass transfer dynamics, leading to spatial disparities in drying rates. Upstream samples dry faster due to higher exposure to hot air, while downstream samples experience delayed moisture loss. The study reveals that deformation patterns and air distribution significantly influence temperature, moisture, and velocity profiles in multi-layer drying. These insights contribute to the development of more uniform and energy-efficient drying strategies for porous food materials.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101449"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal analysis of metal foam integrated heatsink for electrified aircraft applications","authors":"Dikshant Sharma ,&nbsp;Lukas Radomsky ,&nbsp;Akilan Mathiazhagan ,&nbsp;Majid Asli ,&nbsp;Klaus Höschler ,&nbsp;Regine Mallwitz","doi":"10.1016/j.ijft.2025.101465","DOIUrl":"10.1016/j.ijft.2025.101465","url":null,"abstract":"<div><div>Metal foams facilitate large heat dissipation in high-power dense systems such as power electronics for electrified propulsion application. This work addresses the cooling of a power semiconductor device with aluminium and copper metal foam integrated hybrid heatsink and its comparative analysis to a conventional finned heatsink using 0D and 3D modelling approach. Two-equation foam model in Fluent is utilized and the numerical approach is validated against experimental dataset. Inlet air velocity is varied such that the Darcy to turbulent regimes of the open-cellular foams are covered. Foam porosities from <span><math><mrow><mo>∼</mo><mn>0</mn><mo>.</mo><mn>85</mn><mo>−</mo><mn>0</mn><mo>.</mo><mn>95</mn></mrow></math></span> with 10–20 PPI are investigated and the thermal performance of the heatsink is found to be independent of the foam material. High porosity (<span><math><mrow><mo>&gt;</mo><mn>0</mn><mo>.</mo><mn>9</mn></mrow></math></span>), 20 PPI foams are found to aid forced-convection by improving the thermal resistance by more than 10% against the 10 PPI counterparts. The hybrid heatsink outperforms the foam-based and conventional heatsink by 40% and 15% respectively when considering the reduction in junction temperatures, while the hydraulic resistance increases 10 times when compared to the conventional one. The 0D thermal resistance model is robust in predicting the junction temperatures for metal foam heatsinks with only a 5%–6% discrepancy for both the 50 W and 100 W heat load scenarios. The key and novel contribution of this study is the integration of detailed 3D simulations of a power electronics cooling environment with the development of a corresponding 0D thermal model. This approach not only eases the physical representation of the system but also enables the model to be extended to diverse heat load conditions.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101465"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanofluid natural convection in trapezoidal annuli: Comparative effects of triangular, circular, and square inner walls","authors":"M.M. Hasan ,&nbsp;M.A. Halim ,&nbsp;M.S. Rana ,&nbsp;S.Y. Jannaty ,&nbsp;M.J. Uddin","doi":"10.1016/j.ijft.2025.101461","DOIUrl":"10.1016/j.ijft.2025.101461","url":null,"abstract":"<div><div>This work presents a novel numerical study on how inner-wall geometry influences natural convection in nanofluid-filled trapezoidal annular cavities, which has not been systematically addressed in previous studies. An Al<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>–water nanofluid is examined in three inner-wall configurations: square (Case 1), circular (Case 2), and triangular (Case 3). The governing equations, formulated under the Boussinesq approximation, are solved using the Galerkin finite element method and validated against established benchmark data. The numerical simulations were conducted for nanoparticle volume fractions in the range of <span><math><mrow><mi>ϕ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>00</mn></mrow></math></span>–0.1, the characteristic length <span><math><mrow><mi>L</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>02</mn></mrow></math></span>–<span><math><mrow><mn>0</mn><mo>.</mo><mn>07</mn><mspace></mspace><mi>m</mi></mrow></math></span>, and particle diameters of <span><math><mrow><msub><mrow><mi>d</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span>–<span><math><mrow><mn>60</mn><mspace></mspace><mi>nm</mi></mrow></math></span>. These ranges were selected to represent typical conditions encountered in nanofluid-based natural convection systems. The results reveal that the circular wall enhances peak velocity, whereas the triangular wall provides more uniform velocity fields, higher average velocity magnitude, and consistently larger Nusselt numbers compared to the square and circular cases. In addition, the triangular geometry ensures more homogeneous temperature and concentration distributions, which is advantageous for stable thermal performance. The study also identifies optimal nanoparticle loading for enhanced convection, while showing that particle sizes beyond <span><math><mrow><mo>∼</mo><mn>60</mn><mspace></mspace><mi>nm</mi></mrow></math></span> lead to suppressed transport phenomena. Aspect ratio and wall shape strongly influence skin-friction behavior, highlighting geometry as a key design parameter. Over time, velocity magnitude, Nusselt number, temperature, and nanoparticle concentration initially exhibit transient fluctuations before reaching steady-state, with Case 3 (triangular inner wall configuration) stabilizing fastest in velocity and concentration and achieving the highest heat transfer efficiency. These findings provide physically grounded design guidelines for engineering compact and efficient nanofluid-based thermal management systems.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101461"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}