{"title":"Magnetohydrodynamic flow of hybrid Ag-CuO/H2O nanofluid past a stretching/shrinking porous plate with viscous-Ohmic dissipation and heat generation/absorption","authors":"","doi":"10.22364/mhd.57.3.7","DOIUrl":"https://doi.org/10.22364/mhd.57.3.7","url":null,"abstract":"","PeriodicalId":18136,"journal":{"name":"Magnetohydrodynamics","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48513401","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}
{"title":"The effect of thermal radiation, velocity slip and viscous dissipation on MHD stagnation-point flow and heat transfer over a shrinking sheet in nanofluids with stability analysis","authors":"","doi":"10.22364/mhd.57.3.3","DOIUrl":"https://doi.org/10.22364/mhd.57.3.3","url":null,"abstract":"","PeriodicalId":18136,"journal":{"name":"Magnetohydrodynamics","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48216409","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}
{"title":"Numerical study of mixed convection and buoyancy ratio on MHD fluid flow beyond an inclined sheet","authors":"","doi":"10.22364/mhd.57.3.2","DOIUrl":"https://doi.org/10.22364/mhd.57.3.2","url":null,"abstract":"","PeriodicalId":18136,"journal":{"name":"Magnetohydrodynamics","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42638519","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}
{"title":"Stagnation point flow and heat transfer over an exponentially stretching/shrinking Riga plate with effects of radiation and heat source/sink","authors":"","doi":"10.22364/mhd.57.3.8","DOIUrl":"https://doi.org/10.22364/mhd.57.3.8","url":null,"abstract":"","PeriodicalId":18136,"journal":{"name":"Magnetohydrodynamics","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43498399","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}
An electric current is passed through the interface of liquid gallium and aqueous electrolyte in a square cross-section cell under a background vertical magnetic field. The oscillation increment of surface waves is calculated from potential measurements at variable current strengths. The surface is also visually observed through transparent side walls. No growing surface waves occur for the Sele parameter as high as 1.5. Instead, a quasi-static surface deformation is caused by the rotation of the metal and electrolyte. The maximum height of this surface deformation increases approximately in proportion to the current. Figs 7, Refs 15.
{"title":"Experimental observation of metal-electrolyte interface stability in a model of liquid metal battery","authors":"","doi":"10.22364/mhd.57.2.3","DOIUrl":"https://doi.org/10.22364/mhd.57.2.3","url":null,"abstract":"An electric current is passed through the interface of liquid gallium and aqueous electrolyte in a square cross-section cell under a background vertical magnetic field. The oscillation increment of surface waves is calculated from potential measurements at variable current strengths. The surface is also visually observed through transparent side walls. No growing surface waves occur for the Sele parameter as high as 1.5. Instead, a quasi-static surface deformation is caused by the rotation of the metal and electrolyte. The maximum height of this surface deformation increases approximately in proportion to the current. Figs 7, Refs 15.","PeriodicalId":18136,"journal":{"name":"Magnetohydrodynamics","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49563898","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}
The present article describes a numerical strategy for the estimation of the shear coefficient of spin viscosity for a ferrofluid sample confined to a cylindrical container and exposed to the effect of an external rotating magnetic field with a low amplitude and frequency. As far as we know, there are no experimental measurements of such coefficient. Furthermore, the few analytical values reported differ in several orders of magnitude. First, we describe briefly the mathematical model of the system and its numerical solution. Then, the definition of the direct and inverse problems is given as a part of the methodology for estimating such coefficient. Finally, we solve the inverse problem using simulated measurements and two global optimization algorithms. We generate this type of measurements by adding white Gaussian noise signals to the numerical solution of the ferrohydrodynamic mathematical model. Several noise levels in the range of 10 to 40 dB were used to increase the number of scenarios for validation purpose. Results showed an excellent agreement between the estimated values and those used in the numerical solution of the mathematical model. A statistical analysis revealed a normal distribution that was dependent on the noise level. This variation did not affect the results, but showed instead the validity of the proposed method. Additionally, this strategy stands as a computational tool for validating experimental results of the future in situ measurements. Tables 7, Figs 11, Refs 17.
{"title":"Shear coefficient of spin viscosity estimation through velocity profiles of a ferrofluid under the effect of an external rotating magnetic field of low amplitude and frequency","authors":"","doi":"10.22364/mhd.57.2.1","DOIUrl":"https://doi.org/10.22364/mhd.57.2.1","url":null,"abstract":"The present article describes a numerical strategy for the estimation of the shear coefficient of spin viscosity for a ferrofluid sample confined to a cylindrical container and exposed to the effect of an external rotating magnetic field with a low amplitude and frequency. As far as we know, there are no experimental measurements of such coefficient. Furthermore, the few analytical values reported differ in several orders of magnitude. First, we describe briefly the mathematical model of the system and its numerical solution. Then, the definition of the direct and inverse problems is given as a part of the methodology for estimating such coefficient. Finally, we solve the inverse problem using simulated measurements and two global optimization algorithms. We generate this type of measurements by adding white Gaussian noise signals to the numerical solution of the ferrohydrodynamic mathematical model. Several noise levels in the range of 10 to 40 dB were used to increase the number of scenarios for validation purpose. Results showed an excellent agreement between the estimated values and those used in the numerical solution of the mathematical model. A statistical analysis revealed a normal distribution that was dependent on the noise level. This variation did not affect the results, but showed instead the validity of the proposed method. Additionally, this strategy stands as a computational tool for validating experimental results of the future in situ measurements. Tables 7, Figs 11, Refs 17.","PeriodicalId":18136,"journal":{"name":"Magnetohydrodynamics","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44943484","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}
We consider a mathematical model of two-dimensional electrically driven laminar axisymmetric circular free shear flows in a cylindrical vessel under the action of an applied axial uniform magnetic field. The mathematical approach is based on the studies by J.C.R. Hunt and W.E. Williams (J. Fluid. Mech., 31, 705, 1968). We solve a system of stationary partial differential equations with two unknown functions of velocity and induced magnetic field. The flows are generated as a result of the interaction of the electric current injected into the liquid and the applied field using one or two pairs of concentric annular electrodes located apart on the end walls. Two lateral free shear layers and two Hartmann layers on the end walls and a quasi-potential flow core between them emerge when the Hartmann number Ha >> 1. As a result, almost all injected current passes through these layers. Depending on the direction of the current injection, coinciding or two counter flows between the end walls are realized. The Hartmann number varies in a range from 2 to 300. When a moderate magnetic field (Ha = 50) is reached, the flow rate and the induced magnetic field flux cease to depend on the magnitude of the applied field but depend on the injected electric current value. Increasing magnetic field leads only to inner restructuring of the flows. Redistributions of velocities and induced magnetic fields, electric current density versus Hartmann number are analyzed. Figs 18, Refs 21.
{"title":"Electrically driven cylindrical free shear flows under an axial uniform magnetic field","authors":"","doi":"10.22364/mhd.57.2.8","DOIUrl":"https://doi.org/10.22364/mhd.57.2.8","url":null,"abstract":"We consider a mathematical model of two-dimensional electrically driven laminar axisymmetric circular free shear flows in a cylindrical vessel under the action of an applied axial uniform magnetic field. The mathematical approach is based on the studies by J.C.R. Hunt and W.E. Williams (J. Fluid. Mech., 31, 705, 1968). We solve a system of stationary partial differential equations with two unknown functions of velocity and induced magnetic field. The flows are generated as a result of the interaction of the electric current injected into the liquid and the applied field using one or two pairs of concentric annular electrodes located apart on the end walls. Two lateral free shear layers and two Hartmann layers on the end walls and a quasi-potential flow core between them emerge when the Hartmann number Ha >> 1. As a result, almost all injected current passes through these layers. Depending on the direction of the current injection, coinciding or two counter flows between the end walls are realized. The Hartmann number varies in a range from 2 to 300. When a moderate magnetic field (Ha = 50) is reached, the flow rate and the induced magnetic field flux cease to depend on the magnitude of the applied field but depend on the injected electric current value. Increasing magnetic field leads only to inner restructuring of the flows. Redistributions of velocities and induced magnetic fields, electric current density versus Hartmann number are analyzed. Figs 18, Refs 21.","PeriodicalId":18136,"journal":{"name":"Magnetohydrodynamics","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43485889","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}
A liquid metal flat jet immersed in a square duct under the influence of a transverse magnetic field is studied experimentally. Two cases are considered: when the applied magnetic field is oriented parallel (coplanar field) or perpendicularly (transverse field) to the initial plane of the jet. The main goal of the study is to investigate the mean flow characteristics and the stages of the jet's transformation. Signals of streamwise velocity at different locations are measured, which allows us to determine average velocity profiles and spatial-temporal characteristics of the velocity field. The two considered configurations are directly compared under the same flow regimes, with the same equipment. Figs 8, Refs 11.
{"title":"Flat liquid metal jet affected by a transverse magnetic field","authors":"","doi":"10.22364/mhd.57.2.6","DOIUrl":"https://doi.org/10.22364/mhd.57.2.6","url":null,"abstract":"A liquid metal flat jet immersed in a square duct under the influence of a transverse magnetic field is studied experimentally. Two cases are considered: when the applied magnetic field is oriented parallel (coplanar field) or perpendicularly (transverse field) to the initial plane of the jet. The main goal of the study is to investigate the mean flow characteristics and the stages of the jet's transformation. Signals of streamwise velocity at different locations are measured, which allows us to determine average velocity profiles and spatial-temporal characteristics of the velocity field. The two considered configurations are directly compared under the same flow regimes, with the same equipment. Figs 8, Refs 11.","PeriodicalId":18136,"journal":{"name":"Magnetohydrodynamics","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47428338","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}
In the article, authors present a numerical method for modelling a laminar-turbulent transition in magnetohydrodynamic flows. The small magnetic Reynolds number approach is considered. Velocity, pressure and electrical potential are decomposed to the sum of state values and finite amplitude perturbations. A solver based on the Nektar++ framework is described. The authors suggest using small-length local perturbations as a transition trigger. They can be imposed by blowing or by electrical enforcing. The stability of the Hartmann flow and the flow in the bend are considered as examples. Tables 4, Figs 19, Refs 28.
{"title":"A simple scenario of the laminar breakdown in liquid metal flows","authors":"","doi":"10.22364/mhd.57.2.5","DOIUrl":"https://doi.org/10.22364/mhd.57.2.5","url":null,"abstract":"In the article, authors present a numerical method for modelling a laminar-turbulent transition in magnetohydrodynamic flows. The small magnetic Reynolds number approach is considered. Velocity, pressure and electrical potential are decomposed to the sum of state values and finite amplitude perturbations. A solver based on the Nektar++ framework is described. The authors suggest using small-length local perturbations as a transition trigger. They can be imposed by blowing or by electrical enforcing. The stability of the Hartmann flow and the flow in the bend are considered as examples. Tables 4, Figs 19, Refs 28.","PeriodicalId":18136,"journal":{"name":"Magnetohydrodynamics","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42911112","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}
The magnetohydrodynamic generator is one of the renewable energy generation methods which is primarily based on the Faradayâs law of electromagnetic induction. This paper presents a detailed review about MHD -- its introduction and further advancement in its technology subsequently. An attempt has been made to make the reader understand the details about its operating principle. The MHD systems, being static, are much more efficient compared to conventional fossil fuel based generating systems. Also, these are more environment friendly as there are no emissions from the MHD generator. This paper also presents different types of MHD generators. The MHD generator can be considered to be a newest, efficient and reliable alternative to the conventional energy conversion system which would help to make a step forward towards the totally sustainable society. Figs 8, Refs 73.
{"title":"Magnetohydrodynamic system -- a need for a sustainable power generation source","authors":"","doi":"10.22364/mhd.57.2.9","DOIUrl":"https://doi.org/10.22364/mhd.57.2.9","url":null,"abstract":"The magnetohydrodynamic generator is one of the renewable energy generation methods which is primarily based on the Faradayâs law of electromagnetic induction. This paper presents a detailed review about MHD -- its introduction and further advancement in its technology subsequently. An attempt has been made to make the reader understand the details about its operating principle. The MHD systems, being static, are much more efficient compared to conventional fossil fuel based generating systems. Also, these are more environment friendly as there are no emissions from the MHD generator. This paper also presents different types of MHD generators. The MHD generator can be considered to be a newest, efficient and reliable alternative to the conventional energy conversion system which would help to make a step forward towards the totally sustainable society. Figs 8, Refs 73.","PeriodicalId":18136,"journal":{"name":"Magnetohydrodynamics","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45579650","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}
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