Pub Date : 2022-03-11DOI: 10.1088/1873-7005/ac5d1e
S. Channouf, M. Jami, A. Mezrhab
In this paper, boiling and condensation phenomena are described on walls with mixed wettability using a hybrid thermal model with multiple relaxation times of the Boltzmann lattice type. We start this study by validating our code. To do so, different simulations are performed namely the spreading of a liquid droplet on an adjustable wettability surface by varying its density, the surface tension for different temperatures around the critical point using Laplace’s law which is used to compute the characteristic parameters (Taylor wavelength λd , characteristic length l0 and characteristic time t0 ), the evaporation of a liquid droplet is evaluated in compraison with the literature work for constant thermal conductivity values. Subsequently, the power law is verified by processing the growth of a liquid droplet for three different cases of wettability. On the other hand, we study the behavior of condensation and boiling processes and their interactions between the boundaries of the solid surface in which they occur. For this purpose, the cavity walls are considered wetting in some areas and non-wetting in others. The results show different behaviors depending on the zones of the walls.
{"title":"Numerical hybrid thermal MRT-LBM for condensation and boiling phenomena on horizontal walls of different wettability","authors":"S. Channouf, M. Jami, A. Mezrhab","doi":"10.1088/1873-7005/ac5d1e","DOIUrl":"https://doi.org/10.1088/1873-7005/ac5d1e","url":null,"abstract":"In this paper, boiling and condensation phenomena are described on walls with mixed wettability using a hybrid thermal model with multiple relaxation times of the Boltzmann lattice type. We start this study by validating our code. To do so, different simulations are performed namely the spreading of a liquid droplet on an adjustable wettability surface by varying its density, the surface tension for different temperatures around the critical point using Laplace’s law which is used to compute the characteristic parameters (Taylor wavelength λd , characteristic length l0 and characteristic time t0 ), the evaporation of a liquid droplet is evaluated in compraison with the literature work for constant thermal conductivity values. Subsequently, the power law is verified by processing the growth of a liquid droplet for three different cases of wettability. On the other hand, we study the behavior of condensation and boiling processes and their interactions between the boundaries of the solid surface in which they occur. For this purpose, the cavity walls are considered wetting in some areas and non-wetting in others. The results show different behaviors depending on the zones of the walls.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47756563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<p><strong>Background: </strong>The derivatives of quercetin is known for their immune-modulating antiviral, anti-blood clotting, antioxidant, and also for its anti-inflammatory efficacy. The current study was therefore conducted to examine the noted novel derivatives of quercetin present in plant sources as an immune modulator and as an antiviral molecule in the COVID-19 disease and also to study their affinity of binding with potential three targets reported for coronavirus, i.e., papain-like protease, spike protein receptor-binding domain, and 3C-like protease. Based on the high-positive drug-likeness score, the reported derivatives of quercetin obtained from an open-source database were further filtered. Compounds with positive and high drug-likeness scores were further predicted for their potential targets using DIGEP-Pred software, and STRING was used to evaluate the interaction between modulated proteins. The associated pathways were recorded based on the Kyoto Encyclopedia of Genes and Genomes pathway database. Docking was performed finally using PyRx having AutoDock Vina to identify the efficacy of binding between quercetin derivatives with papain-like protease, spike protein receptor-binding domain, and 3C-like protease. The ligand that scored minimum binding energy was chosen to visualize the interaction between protein and ligand. Normal mode analysis in internal coordinates was done with normal mode analysis to evaluate the physical movement and stability of the best protein-ligand complexes using the iMODS server.</p><p><strong>Results: </strong>Forty bioactive compounds with the highest positive drug-likeness scores were identified. These 40 bioactives were responsible for regulating different pathways associated with antiviral activity and modulation of immunity. Finally, three lead molecules were identified based on the molecular docking and dynamics simulation studies with the highest anti-COVID-19 and immunomodulatory potentials. Standard antiviral drug remdesivir on docking showed a binding affinity of - 5.8 kcal/mol with PLpro, - 6.4 kcal/mol with 3CLpro, and - 8.6 kcal/mol with spike protein receptor-binding domain of SARS-CoV-2, the discovered hit molecules quercetin 3-O-arabinoside 7-O-rhamnoside showed binding affinity of - 8.2 kcal/mol with PLpro, whereas quercetin 3-[rhamnosyl-(1- > 2)-alpha-L-arabinopyranoside] and quercetin-3-neohesperidoside-7-rhamnoside was predicted to have a binding affinity of - 8.5 kcal/mol and - 8.8 kcal/mol with spike protein receptor-binding domain and 3CLpro respectively CONCLUSION: Docking study revealed quercetin 3-O-arabinoside 7-O-rhamnoside to possess the highest binding affinity with papain-like protease, quercetin 3-[rhamnosyl-(1- > 2)-alpha-L-arabinopyranoside] with spike protein receptor-binding domain, and quercetin-3-neohesperidoside-7-rhamnoside with 3C-like protease and all the protein-ligand complexes were found to be stable after performing the normal mode analysis of the comp
{"title":"In silico discovery of 3 novel quercetin derivatives against papain-like protease, spike protein, and 3C-like protease of SARS-CoV-2.","authors":"Kunal Bhattacharya, Ripunjoy Bordoloi, Nongmaithem Randhoni Chanu, Ramen Kalita, Bhargab Jyoti Sahariah, Atanu Bhattacharjee","doi":"10.1186/s43141-022-00314-7","DOIUrl":"10.1186/s43141-022-00314-7","url":null,"abstract":"<p><strong>Background: </strong>The derivatives of quercetin is known for their immune-modulating antiviral, anti-blood clotting, antioxidant, and also for its anti-inflammatory efficacy. The current study was therefore conducted to examine the noted novel derivatives of quercetin present in plant sources as an immune modulator and as an antiviral molecule in the COVID-19 disease and also to study their affinity of binding with potential three targets reported for coronavirus, i.e., papain-like protease, spike protein receptor-binding domain, and 3C-like protease. Based on the high-positive drug-likeness score, the reported derivatives of quercetin obtained from an open-source database were further filtered. Compounds with positive and high drug-likeness scores were further predicted for their potential targets using DIGEP-Pred software, and STRING was used to evaluate the interaction between modulated proteins. The associated pathways were recorded based on the Kyoto Encyclopedia of Genes and Genomes pathway database. Docking was performed finally using PyRx having AutoDock Vina to identify the efficacy of binding between quercetin derivatives with papain-like protease, spike protein receptor-binding domain, and 3C-like protease. The ligand that scored minimum binding energy was chosen to visualize the interaction between protein and ligand. Normal mode analysis in internal coordinates was done with normal mode analysis to evaluate the physical movement and stability of the best protein-ligand complexes using the iMODS server.</p><p><strong>Results: </strong>Forty bioactive compounds with the highest positive drug-likeness scores were identified. These 40 bioactives were responsible for regulating different pathways associated with antiviral activity and modulation of immunity. Finally, three lead molecules were identified based on the molecular docking and dynamics simulation studies with the highest anti-COVID-19 and immunomodulatory potentials. Standard antiviral drug remdesivir on docking showed a binding affinity of - 5.8 kcal/mol with PLpro, - 6.4 kcal/mol with 3CLpro, and - 8.6 kcal/mol with spike protein receptor-binding domain of SARS-CoV-2, the discovered hit molecules quercetin 3-O-arabinoside 7-O-rhamnoside showed binding affinity of - 8.2 kcal/mol with PLpro, whereas quercetin 3-[rhamnosyl-(1- > 2)-alpha-L-arabinopyranoside] and quercetin-3-neohesperidoside-7-rhamnoside was predicted to have a binding affinity of - 8.5 kcal/mol and - 8.8 kcal/mol with spike protein receptor-binding domain and 3CLpro respectively CONCLUSION: Docking study revealed quercetin 3-O-arabinoside 7-O-rhamnoside to possess the highest binding affinity with papain-like protease, quercetin 3-[rhamnosyl-(1- > 2)-alpha-L-arabinopyranoside] with spike protein receptor-binding domain, and quercetin-3-neohesperidoside-7-rhamnoside with 3C-like protease and all the protein-ligand complexes were found to be stable after performing the normal mode analysis of the comp","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":"25 1","pages":"43"},"PeriodicalIF":0.0,"publicationDate":"2022-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8905286/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78041575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-07DOI: 10.1088/1873-7005/ac5b15
I. Nikulin, V. Demin, A. V. Perminov
The paper concerns some aspects of the induction melting technology improvement. The generalized mathematical model is presented which contains governing equations for the alternating magnetic field (AMF) diffusion into the liquid metal, heat and mass transfer in the melt and elastic deformation of the dielectric film covering partially the melt surface. The integral strain criterion is suggested which describes the total stress excited in the film by the melt motion. The model validation results are described. The influence of the film size on its stress–strain state is studied numerically for different values of external AMF frequency and strength. We calculate and classify realizable surface flow regimes depending on the AMF frequency and model, how this near-surface flow deforms the film of different sizes. An integral strain criterion is introduced, which lets to estimate the film break condition. The map of regimes is drawn which demonstrates the possible film radii at which the film does not break and does not deform depending on the AMF frequency and strength. It is shown, that integral strain criterion predicts well the film stress–strain state and conforms to the map of regimes. The results of numerical modeling, technique of the integral strain criterion calculation and examples of its application are given.
{"title":"Surface film deformation by melt moving in an alternating magnetic field and the integral criterion of such film stability","authors":"I. Nikulin, V. Demin, A. V. Perminov","doi":"10.1088/1873-7005/ac5b15","DOIUrl":"https://doi.org/10.1088/1873-7005/ac5b15","url":null,"abstract":"The paper concerns some aspects of the induction melting technology improvement. The generalized mathematical model is presented which contains governing equations for the alternating magnetic field (AMF) diffusion into the liquid metal, heat and mass transfer in the melt and elastic deformation of the dielectric film covering partially the melt surface. The integral strain criterion is suggested which describes the total stress excited in the film by the melt motion. The model validation results are described. The influence of the film size on its stress–strain state is studied numerically for different values of external AMF frequency and strength. We calculate and classify realizable surface flow regimes depending on the AMF frequency and model, how this near-surface flow deforms the film of different sizes. An integral strain criterion is introduced, which lets to estimate the film break condition. The map of regimes is drawn which demonstrates the possible film radii at which the film does not break and does not deform depending on the AMF frequency and strength. It is shown, that integral strain criterion predicts well the film stress–strain state and conforms to the map of regimes. The results of numerical modeling, technique of the integral strain criterion calculation and examples of its application are given.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45833494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-16DOI: 10.1088/1873-7005/ac55ed
K. Usman, K. Walayat, R. Mahmood, S. Jabeen
We have examined the effects caused on the motion and sedimentation of a free falling solid particle by the hydrodynamic forces acting on the particle’s surface arising when particle is close to wall. Drag and lift coefficients for a settling particle inside a narrow domain are calculated. An Eulerian mesh is adopted for computing the motion of free moving solid particles through the domain. The combined particle and fluid mixture is treated with a fictitious boundary method approach. To avoid particle-wall collisions, an approach proposed by Singh, Glowinsk and coauthors is used to handle such interactions. The particulate flow is computed using multigrid finite element solver FEATFLOW (Finite element analysis tool for flow problems). Numerical experiments are performed by decreasing domain widths for a single falling particle. The size and density of the particle is varied to inspect the particle paths. The behavior of the particle and its interaction with wall while it is moving inside constricted domains is analyzed. Results for the drag and lift forces on the surface of particle are presented and compared with the reference values.
{"title":"Wall effects on a falling solid particle in an infinite channel","authors":"K. Usman, K. Walayat, R. Mahmood, S. Jabeen","doi":"10.1088/1873-7005/ac55ed","DOIUrl":"https://doi.org/10.1088/1873-7005/ac55ed","url":null,"abstract":"We have examined the effects caused on the motion and sedimentation of a free falling solid particle by the hydrodynamic forces acting on the particle’s surface arising when particle is close to wall. Drag and lift coefficients for a settling particle inside a narrow domain are calculated. An Eulerian mesh is adopted for computing the motion of free moving solid particles through the domain. The combined particle and fluid mixture is treated with a fictitious boundary method approach. To avoid particle-wall collisions, an approach proposed by Singh, Glowinsk and coauthors is used to handle such interactions. The particulate flow is computed using multigrid finite element solver FEATFLOW (Finite element analysis tool for flow problems). Numerical experiments are performed by decreasing domain widths for a single falling particle. The size and density of the particle is varied to inspect the particle paths. The behavior of the particle and its interaction with wall while it is moving inside constricted domains is analyzed. Results for the drag and lift forces on the surface of particle are presented and compared with the reference values.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42477955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-15DOI: 10.1088/1873-7005/ac5527
S. Kundu, Titas Chattopadhyay
Cellular secondary flows are inevitably present in turbulent flows through ducts, natural or artificial channels, and compound channels. Secondary currents significantly modify the characteristics of turbulent quantities, the pattern of primary flow velocity by causing dip-phenomenon. To understand the detailed mechanism and hidden cause, modelling of secondary flow velocities is crucial. In this study, proper mathematical models of secondary flow velocities along vertical and transverse directions are proposed for steady and uniform turbulent flow through wide open channels with equal smooth and rough bed strips. Starting from the continuity and the Reynolds averaged Navier-Stokes equations, governing equation for secondary velocity is derived first and then using appropriate boundary conditions (no-slip boundary conditions at channel bottom and free surface, and maximum vertical velocity in magnitude at the interface of two cellular secondary cells and at mid-depth of the channel. All these conditions are consistent with several experimental observations). A new model of the streamwise Reynolds shear stress is proposed for the entire cross-sectional plane and using it, the analytical solutions are obtained. Proposed models include the effects of viscosity of the fluid and the eddy viscosity model of turbulence. All suggested models are validated with existing experimental data in rectangular open-channel flows, compound open channel flows, and duct flows, and satisfactory results are obtained. Furthermore, models are also compared with existing empirical models from literature to show the effectiveness and superiority of proposed models. Apart from these, the obtained results from this study are used to investigate the effects of vertical and transverse secondary flow velocities on the settling velocity vector in a cross-sectional plane. Effective alternative models for the settling velocity vector are suggested. The model of settling velocity vector is also compared with the existing model. Finally, all results are justified from physical viewpoints.
{"title":"Analysis and validation of mathematical models of secondary velocities along vertical and transverse directions in wide open-channel turbulent flows","authors":"S. Kundu, Titas Chattopadhyay","doi":"10.1088/1873-7005/ac5527","DOIUrl":"https://doi.org/10.1088/1873-7005/ac5527","url":null,"abstract":"\u0000 Cellular secondary flows are inevitably present in turbulent flows through ducts, natural or artificial channels, and compound channels. Secondary currents significantly modify the characteristics of turbulent quantities, the pattern of primary flow velocity by causing dip-phenomenon. To understand the detailed mechanism and hidden cause, modelling of secondary flow velocities is crucial. In this study, proper mathematical models of secondary flow velocities along vertical and transverse directions are proposed for steady and uniform turbulent flow through wide open channels with equal smooth and rough bed strips. Starting from the continuity and the Reynolds averaged Navier-Stokes equations, governing equation for secondary velocity is derived first and then using appropriate boundary conditions (no-slip boundary conditions at channel bottom and free surface, and maximum vertical velocity in magnitude at the interface of two cellular secondary cells and at mid-depth of the channel. All these conditions are consistent with several experimental observations). A new model of the streamwise Reynolds shear stress is proposed for the entire cross-sectional plane and using it, the analytical solutions are obtained. Proposed models include the effects of viscosity of the fluid and the eddy viscosity model of turbulence. All suggested models are validated with existing experimental data in rectangular open-channel flows, compound open channel flows, and duct flows, and satisfactory results are obtained. Furthermore, models are also compared with existing empirical models from literature to show the effectiveness and superiority of proposed models. Apart from these, the obtained results from this study are used to investigate the effects of vertical and transverse secondary flow velocities on the settling velocity vector in a cross-sectional plane. Effective alternative models for the settling velocity vector are suggested. The model of settling velocity vector is also compared with the existing model. Finally, all results are justified from physical viewpoints.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42696697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-04DOI: 10.1088/1873-7005/ac522d
S. Maslowe
This paper presents an investigation of the stability of a vortex with azimuthal velocity profile Vˉ=1−1−εr2e−r2/r . When ε = 0, the Lamb–Oseen vortex model is recovered. Although the Lamb–Oseen vortex supports propagating waves known as Kelvin waves, the flow is stable according to Rayleigh’s circulation criterion. In this paper, on the other hand, the modified vortex profile admits linearly unstable disturbances for ε > 0 and we investigate their characteristics. These may be either axisymmetric or non-axisymmetric, but we find that the axisymmetric perturbations have the largest growth rates. When their growth rates are small, it becomes very difficult to solve the linear equation governing the axisymmetric perturbations because the eigenfunctions have a rapid exponential growth as one moves outward radially from the vortex center. To deal with such cases, a modified Riccati transformation was employed and found to be effective in solving the associated eigenvalue problem.
{"title":"Linear instability of a perturbed Lamb–Oseen vortex","authors":"S. Maslowe","doi":"10.1088/1873-7005/ac522d","DOIUrl":"https://doi.org/10.1088/1873-7005/ac522d","url":null,"abstract":"This paper presents an investigation of the stability of a vortex with azimuthal velocity profile Vˉ=1−1−εr2e−r2/r . When ε = 0, the Lamb–Oseen vortex model is recovered. Although the Lamb–Oseen vortex supports propagating waves known as Kelvin waves, the flow is stable according to Rayleigh’s circulation criterion. In this paper, on the other hand, the modified vortex profile admits linearly unstable disturbances for ε > 0 and we investigate their characteristics. These may be either axisymmetric or non-axisymmetric, but we find that the axisymmetric perturbations have the largest growth rates. When their growth rates are small, it becomes very difficult to solve the linear equation governing the axisymmetric perturbations because the eigenfunctions have a rapid exponential growth as one moves outward radially from the vortex center. To deal with such cases, a modified Riccati transformation was employed and found to be effective in solving the associated eigenvalue problem.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49354376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-04DOI: 10.1088/1873-7005/ac522c
Xiangbin Chen, W. Xiao, Ruiyan Gong, X. Yao, Shaofeng Hu
Ventilation bubble is widely used to reduce friction drag of object travelling in fluid. A large number of experimental studies are performed on the ventilation bubble in water tunnel, while little is known about it around vertically moving cylinder under reduced pressure. We aim to investigate dynamics of the ventilation bubble in vertically moving case. To support the study, a specialized experiment set-up is designed, based on which images of ventilation bubble around vertically moving cylinder under reduced ambient pressure can be captured and experiments are conducted to study the influence of velocities and flow rate on the ventilation bubble dynamics. In detail,We first describe the development of ventilation bubble and details of re-entrant jet. In addition to that, two types of re-entrant jets are observed, and the maximum velocity of re-entrant jet is obtained. Besides, four modes of development of ventilation bubbles' closure patterns are concluded. Finally, geometric features of ventilation bubble are obtained through image processing which are then described and analysed in detail.The above results contribute to the research on the control of vertically moving cylinder through ventilation bubble.
{"title":"Experimental investigation of ventilation bubble dynamics around a vertically moving cylinder under reduced ambient pressure","authors":"Xiangbin Chen, W. Xiao, Ruiyan Gong, X. Yao, Shaofeng Hu","doi":"10.1088/1873-7005/ac522c","DOIUrl":"https://doi.org/10.1088/1873-7005/ac522c","url":null,"abstract":"\u0000 Ventilation bubble is widely used to reduce friction drag of object travelling in fluid. A large number of experimental studies are performed on the ventilation bubble in water tunnel, while little is known about it around vertically moving cylinder under reduced pressure. We aim to investigate dynamics of the ventilation bubble in vertically moving case. To support the study, a specialized experiment set-up is designed, based on which images of ventilation bubble around vertically moving cylinder under reduced ambient pressure can be captured and experiments are conducted to study the influence of velocities and flow rate on the ventilation bubble dynamics. In detail,We first describe the development of ventilation bubble and details of re-entrant jet. In addition to that, two types of re-entrant jets are observed, and the maximum velocity of re-entrant jet is obtained. Besides, four modes of development of ventilation bubbles' closure patterns are concluded. Finally, geometric features of ventilation bubble are obtained through image processing which are then described and analysed in detail.The above results contribute to the research on the control of vertically moving cylinder through ventilation bubble.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44614212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-31DOI: 10.1088/1873-7005/ac505d
A N M Mominul Islam Mukut, H. Afroz
Control of flow separation is a great issue to deal with a moving body to ensure its proper aerodynamic characteristics. To achieve this, various methods including active and passive control are suggested depends upon the flow characteristics and the surface in which control is necessary. To make the better use of both active and passive method of flow control this article proposed a new type of Double Sided Plasma Actuator (DSPVG) to overcome the drag penalty of conventional vortex generators (VGs) that commonly used in controlling flow and to use actively control. In this regard, the effectiveness of DSPVG has been numerically and experimentally investigated in a separated flow region of a 20 diffuser of an open type tunnel. DSPVG is placed at the upstream of separation location normal to the surface as like as conventional VG except zero angle with flow direction. Both numerical and experimental results of DSPVG are compared with that of VG and baseline flow and better agreements are found. Moreover, DSPVG has shown better separation supression ability than conventional VGs due to its dual vortices. It is found that DSPVG significantly delay the separation. A freestream flow of 4 m/s is used for experiments and numerical computations.
{"title":"Numerical investigation of double sided plasma vortex generator in separation control","authors":"A N M Mominul Islam Mukut, H. Afroz","doi":"10.1088/1873-7005/ac505d","DOIUrl":"https://doi.org/10.1088/1873-7005/ac505d","url":null,"abstract":"\u0000 Control of flow separation is a great issue to deal with a moving body to ensure its proper aerodynamic characteristics. To achieve this, various methods including active and passive control are suggested depends upon the flow characteristics and the surface in which control is necessary. To make the better use of both active and passive method of flow control this article proposed a new type of Double Sided Plasma Actuator (DSPVG) to overcome the drag penalty of conventional vortex generators (VGs) that commonly used in controlling flow and to use actively control. In this regard, the effectiveness of DSPVG has been numerically and experimentally investigated in a separated flow region of a 20 diffuser of an open type tunnel. DSPVG is placed at the upstream of separation location normal to the surface as like as conventional VG except zero angle with flow direction. Both numerical and experimental results of DSPVG are compared with that of VG and baseline flow and better agreements are found. Moreover, DSPVG has shown better separation supression ability than conventional VGs due to its dual vortices. It is found that DSPVG significantly delay the separation. A freestream flow of 4 m/s is used for experiments and numerical computations.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42799726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-31DOI: 10.1088/1873-7005/ac505c
S. Bansal, T. Gill
In this work, we have analyzed the impact of polarisation force, angle of obliqueness under the influence of nonadiabatic dust charge fluctuation on shock waves formation in magneto rotating plasma. The present plasma model is consisting of negatively charged dust grains, Maxwellian electrons, nonextensive ions. The dissipation is introduced in the system via nonadiabaticity, a new mechanism for the formation of shock waves. Using standard reductive perturbation method, nonlinear equation namely Korteweg-de Vries Burgers (KdVB) equation is derived and solution is obtained using the Tanh method. It is shown that dust charge fluctuation is the main source of dissipation. We have studied the various parameteric influences on such shock structure and also showed how the gradual variations of these parameter affect the generation and structure of the shocks in their respective domain. Much of experiments on dusty plasma with nonadiabatic dust charge fluctuation will benefit from the parametric study.
{"title":"Shock formation in magnetized plasma under the influence of Polarization force and nonadiabaticity of dust charge variation","authors":"S. Bansal, T. Gill","doi":"10.1088/1873-7005/ac505c","DOIUrl":"https://doi.org/10.1088/1873-7005/ac505c","url":null,"abstract":"\u0000 In this work, we have analyzed the impact of polarisation force, angle of obliqueness under the influence of nonadiabatic dust charge fluctuation on shock waves formation in magneto rotating plasma. The present plasma model is consisting of negatively charged dust grains, Maxwellian electrons, nonextensive ions. The dissipation is introduced in the system via nonadiabaticity, a new mechanism for the formation of shock waves. Using standard reductive perturbation method, nonlinear equation namely Korteweg-de Vries Burgers (KdVB) equation is derived and solution is obtained using the Tanh method. It is shown that dust charge fluctuation is the main source of dissipation. We have studied the various parameteric influences on such shock structure and also showed how the gradual variations of these parameter affect the generation and structure of the shocks in their respective domain. Much of experiments on dusty plasma with nonadiabatic dust charge fluctuation will benefit from the parametric study.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47908055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-28DOI: 10.1088/1873-7005/ac4ff6
L. M. Lin, Z. Tan
In the present paper, the spatio-temporal evolution of the vorticity field in the second wake instability, i.e. (pure) mode B is investigated to understand the wake vortex dynamics and sign relationships among the three vorticity components. Direct numerical simulation of the flow past a circular cylinder in the three-dimensional (3D) wake transition is performed, typically at a Reynolds number of 300. According to the time histories of fluid forces and frequency analysis, three different stages are identified. In the fully developed wake (FDW), the spanwise vortex core is almost two-dimensional, while the vortex braid is 3D due to the dominant streamwise interaction. However, streamwise and vertical vorticities owing to the intrinsic 3D instability are already generated first on cylinder surfaces early in the computational transition (CT). The evolution of additional vorticities with the same features as mode B shows that (pure) mode B could already be formed in the late CT. In the FDW, a special sign symmetry of these additional vorticities on the rear surface is observed, which is exactly opposite to that in (pure) mode B. Similarly, the two sign laws found in (pure) mode A are also verified in three typical regions, independent of the Reynolds number, for (pure) mode B. Particularly, the mechanism for the physical origin of streamwise and vertical vortices in the shear layers is the vortex generation on the wall first and then dominant vortex induction just near the wall. The entire process of the formation and shedding of vortices with three components of vorticity is first and completely illustrated. Other characteristics of the evolution of mode B are presented in detail.
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