Natural convection flow in enclosure has different applications such as room ventilation, heat exchangers, the cooling system of a building etc. The Finite-Element method based on the Galerkin weighted residual approa...Natural convection flow in enclosure has different applications such as room ventilation, heat exchangers, the cooling system of a building etc. The Finite-Element method based on the Galerkin weighted residual approach is used to solve two-dimensional governing mass, momentum and energy-equations for natural convection flow in the presence of a magnetic field on a roof top with semi-circular heater. In the enclosure the horizontal lower wall was heated, the vertical two walls were adiabatic, inside the semi-circular heater, the wavy top wall cooled. The parameters Rayleigh number, Hartmann number and Prandtl number are considered. The effects of the Hartmann number and Rayleigh number on the streamlines, isotherms, velocity profiles and average Nusselt number are examined graphically. The local Nusselt number and the average Nusselt number of the heated portion of the enclosure with the semi-circular heater are presented in this paper. Finally, for the validation of the existing work, the current results are compared with published results and the auspicious agreement is achieved.展开更多
Let(u,B)be a strong solution of the magneto-hydrodynamic system on three dimensional torus T^(3).In this note,using the properties of the curl operator,we show that‖(▽×(u-B),▽×(u+B))(·,t)‖L^(1)+1/2v...Let(u,B)be a strong solution of the magneto-hydrodynamic system on three dimensional torus T^(3).In this note,using the properties of the curl operator,we show that‖(▽×(u-B),▽×(u+B))(·,t)‖L^(1)+1/2v‖(u-B,u+B)(·,t)‖_(L^(2))^(2)is decreasing in time t as long as the solution(u,B)(·,t)exists,where∇×w means the curl of the vector function w,and v>0 is the viscosity coefficient.展开更多
We investigate the Cauchy problem for the 3D magneto-hydrodynamics equations with only horizontal dissipation for the small initial data. With the help of the dissipation in the horizontal direction and the structure ...We investigate the Cauchy problem for the 3D magneto-hydrodynamics equations with only horizontal dissipation for the small initial data. With the help of the dissipation in the horizontal direction and the structure of the system, we analyze the properties of the decay of the solution and apply these decay properties to get the global regularity of the solution. In the process, we mainly use the frequency decomposition in Green's function method and energy method.展开更多
This work investigates thermal enhancement in fluid flow over a nonlinear stretching sheet.The thickness of the sheet is variable and the flow of the fluid is affected by solar radiation energy with Thompson and Troia...This work investigates thermal enhancement in fluid flow over a nonlinear stretching sheet.The thickness of the sheet is variable and the flow of the fluid is affected by solar radiation energy with Thompson and Troian slip effects.The flow is magnetized by applying a magnetic field in the normal direction to the flow system.Moreover,thermal transport is controlled by incorporating the Cattaneo-Christov heat fluid model into the flow problem.The governing equations,initially framed in their dimensional form,are meticulously transformed into a dimensionless framework to simplify the analysis.These dimensionless equations are then solved using the homotopy analysis method(HAM).It is observed in this study that upsurges in the stagnation parameter,critical shear rate and velocity slip factor augment the velocity distribution while reducing the thermal profiles.The velocity distribution deteriorates while the thermal profiles are amplified with expansions in the magnetic factor and power law index.The thermal distribution also increases with rising Prandtl number and radiation factor.Augmentation of the power-law index,velocity slip parameter,critical shear rate,magnetic factor and stagnation parameter leads to an increased Nusselt number.The modeled problem is validated by comparing the current results with established work for different values of nonlinear stretching factor n in terms of the drag force and thermal flow rate at η=0,and a good agreement is observed between the current and established results.展开更多
The present exploration is conducted to describe the motion of viscous fluid embedded in squeezed channel under the applied magnetics effects.The processes of heat and mass transport incorporate the temperature-depend...The present exploration is conducted to describe the motion of viscous fluid embedded in squeezed channel under the applied magnetics effects.The processes of heat and mass transport incorporate the temperature-dependent binary chemical reaction with modified Arrhenius theory of activation energy function which is not yet disclosed for squeezing flow mechanism.The flow,heat and mass regime are exposed to be governed via dimensionless,highly non-linear,ordinary differential equations (ODEs) under no-slip walls boundary conditions.A well-tempered analytical convergent procedure is adopted for the solutions of boundary value problem.A detailed study is accounted through graphs in the form of flow velocity field,temperature and fluid concentration distributions for various emerging parameters of enormous interest.Skin-friction,Nusselt and Sherwood numbers have been acquired and disclosed through plots.The results indicate that fluid temperature follows an increasing trend with dominant dimensionless reaction rate σ and activation energy parameter E.However,an increment in σ and E parameters is found to decline in fluid concentration.The current study arises numerous engineering and industrial processes including polymer industry,compression and injection shaping,lubrication system,formation of paper sheets,thin fiber,molding of plastic sheets.In the area of chemical engineering,geothermal engineering,cooling of nuclear reacting,nuclear or chemical system,bimolecular reactions,biochemical process and electrically conducting polymeric flows can be controlled by utilizing magnetic fields.Motivated by such applications,the proposed study has been developed.展开更多
This paper introduces the notion of Tokamak Magneto-Hydrodynamics （TMHD）, which explicitly reflects the anisotropy of a high temperature tokamak plasma. The set of TMHD equations is formulated for simulation of macr...This paper introduces the notion of Tokamak Magneto-Hydrodynamics （TMHD）, which explicitly reflects the anisotropy of a high temperature tokamak plasma. The set of TMHD equations is formulated for simulation of macroscopic plasma dynamics and disruptions in tokamaks. Free from the Courant restriction on the time step, this set of equations is adequate to plasma dynamics with realistic parameters of high performance plasmas and does not require any extension of the MHD plasma model. At the same time, TMHD requires the use of magnetic field aligned numerical grids. Examples of their use in 2-dimensional cases of tokamak equilibria and dynamics of the wall touching kink mode are presented. For the 3-dimensional case of an ergodic magnetic field, this paper introduces the reference magnetic coordinates as a practical algorithm for generating adaptive grids for TMHD.展开更多
This article proves the logarithmically improved Serrin＇s criterion for solutions of the 3D generalized magneto-hydrodynamic equations in terms of the gradient of the velocity field, which can be regarded as improvem...This article proves the logarithmically improved Serrin＇s criterion for solutions of the 3D generalized magneto-hydrodynamic equations in terms of the gradient of the velocity field, which can be regarded as improvement of results in [10] （Luo Y W. On the regularity of generalized MHD equations. J Math Anal Appl, 2010, 365： 806-808） and [18] （Zhang Z J. Remarks on the regularity criteria for generalized MHD equations. J Math Anal Appl, 2011, 375：799 802）.展开更多
This paper concerns the Cauchy problem of the 3D generalized incompressible magneto-hydrodynamic(GMHD) equations. By using the Fourier localization argument and the Littlewood-Paley theory, we get local well-posedness...This paper concerns the Cauchy problem of the 3D generalized incompressible magneto-hydrodynamic(GMHD) equations. By using the Fourier localization argument and the Littlewood-Paley theory, we get local well-posedness results of the GMHD equations with large initial data(u0, b0) belonging to the critical Fourier-Besov-Morrey spaces FN^1-2α+3/p'+λ/pp,λ,q(R^3) Moreover, stability of global solutions is also discussed.展开更多
The approximate solution of the magneto-hydrodynamic （MHD） boundary layer flow over a nonlinear stretching sheet is obtained by combining the Lie symmetry method with the homotopy perturbation method. The approximat...The approximate solution of the magneto-hydrodynamic （MHD） boundary layer flow over a nonlinear stretching sheet is obtained by combining the Lie symmetry method with the homotopy perturbation method. The approximate solution is tabulated, plotted for the values of various parameters and compared with the known solutions. It is found that the approximate solution agrees very well with the known numerical solutions, showing the reliability and validity of the present work.展开更多
This paper presents an integrated research scheme for vector deflection and energy extraction in a gas plasma jet under Magneto-Hydrodynamic(MHD)control.A MHDcontrolled thrust-vector test rig was used to conduct the e...This paper presents an integrated research scheme for vector deflection and energy extraction in a gas plasma jet under Magneto-Hydrodynamic(MHD)control.A MHDcontrolled thrust-vector test rig was used to conduct the experimental research.A gas plasma was obtained by injecting ionization seeds of Cs2CO3 into the combustion chamber via artificially forced ionization.The effects of the gas temperature and ionization seed mass fraction on the plasma jet deflection and energy extraction were experimentally verified under an applied magnetic field.The experimental results were analyzed theoretically.The results showed that the deflection amplitude of the gas plasma jet and the extracted voltage signal intensity increased with increasing gas temperature and the ionization seed mass fraction.The extracted dynamic voltage signals proved that the ionization seeds of Cs2CO3 induced gas ionization at 1173 K.The experiment verified that it is feasible to simultaneously achieve jet deflection and extract energy under the action of an external magnetic field.展开更多
The work is devoted to the fractional characterization of time-dependent coupled convection-diffusion systems arising in magnetohydrodynamics(MHD)flows.The time derivative is expressed by means of Caputo’s fractional...The work is devoted to the fractional characterization of time-dependent coupled convection-diffusion systems arising in magnetohydrodynamics(MHD)flows.The time derivative is expressed by means of Caputo’s fractional derivative concept,while the model is solved via the full-spectral method(FSM)and the semi-spectral scheme(SSS).The FSM is based on the operational matrices of derivatives constructed by using higher-order orthogonal polynomials and collocation techniques.The SSS is developed by discretizing the time variable,and the space domain is collocated by using equal points.A detailed comparative analysis is made through graphs for various parameters and tables with existing literature.The contour graphs are made to show the behaviors of the velocity and magnetic fields.The proposed methods are reasonably efficient in examining the behavior of convection-diffusion equations arising in MHD flows,and the concept may be extended for variable order models arising in MHD flows.展开更多
The present work is an analysis on the ElectroMagnetic Lorentz Force Velocimetry(EM-LFV).This noncontact flow measurement technique is based on evaluating the Lorentz force generated by the interactions of an electric...The present work is an analysis on the ElectroMagnetic Lorentz Force Velocimetry(EM-LFV).This noncontact flow measurement technique is based on evaluating the Lorentz force generated by the interactions of an electrically conducting fluid with a localized magnetic field that is produced by electromagnets.Analytical and numerical calculations were carried out as a continuation of a previous work published by Thess et al.The objective is to establish the behavior of the Lorentz force as a function of the main geometric parameters considered in the studied geometry. Thus we present here the evolution of the Lorentz force induced in a translating cylindrical solid body and the coefficient of sensitivity of the flowmeter thanks to numerical simulations in respect with the main geometrical parameters of the problem.展开更多
In this paper, phenomena of superposability and self superposability in hydrodynamics and magneto hydrodynamics have been discussed. One of the most important applications of superposability in hydrodynamics is the co...In this paper, phenomena of superposability and self superposability in hydrodynamics and magneto hydrodynamics have been discussed. One of the most important applications of superposability in hydrodynamics is the construction of exact analytic solution of the basic equation of fluid dynamics. Kapur and Bhatia have given a simple idea that if two velocity vectors have self superposable and mutually superposable motion then sum or difference of these two is self superposable and vice versa and if each of the vector is superposable on the third then their sum and difference are also superposable on the third. For superposability in magneto-hydrodynamics many mathematicians like Ram Moorthy, Ram Ballabh, Mittal, Kapur & Bhatia and Gold & Krazyblocki have defined it in various ways, especially Kapur & Bhatia generalized the well-known work on superposability by Ram Ballabh to the case of viscous incompressible electrically conducting fluids in the presence of magnetic field. We found the relationship of two basic vectors for two important curvilinear coordinate systems for their use in our work. We’ve found the equations of div, curl and grad for a unit vector in parabolic cylinder coordinates and ellipsoidal coordinates for further use.展开更多
Based on results obtained from the study for MHD （magneto-hydrodynamics） of advective accretion disk, which are applied to real source showing typical values for CBS （close binary star-system）, it will investigate...Based on results obtained from the study for MHD （magneto-hydrodynamics） of advective accretion disk, which are applied to real source showing typical values for CBS （close binary star-system）, it will investigate on self-structuring in the disk under the impact of the distribution of leading parameters （density, velocity ...）. The paper is considering the problem of development of the corona and will analyze the process of interaction of the plasma with the magnetic field in connection to support for the instabilities.展开更多
In this article, we present accurate analytical solutions for boundary layer flow and heat transfer of an incompressible and electrically conducting viscoelastic fluid over a linearly stretching surface subject to a t...In this article, we present accurate analytical solutions for boundary layer flow and heat transfer of an incompressible and electrically conducting viscoelastic fluid over a linearly stretching surface subject to a transverse uniform magnetic field using the homotopy analysis method （HAM） for two general types of non-isothermal boundary conditions. In addition, we demonstrate that the previously reported analytical solutions for the temperature field given in terms of Kummer＇s function do not converge at the boundary. We provide a graphical and numerical demonstration of the convergence of the HAM solutions and tabulate the effects of various parameters on the skin friction coefficient and wall heat transfer.展开更多
Project New Orion entails a pulsed nuclear space propulsion system that utilizes photofission through the implementation of an ultra-intense laser. The historical origins derive from the endeavors of Project Orion, wh...Project New Orion entails a pulsed nuclear space propulsion system that utilizes photofission through the implementation of an ultra-intense laser. The historical origins derive from the endeavors of Project Orion, which utilized thermonuclear devices to impart a considerable velocity increment on the respective spacecraft. The shear magnitude of Project Orion significantly detracts from the likelihood of progressive research development testing and evaluation. Project New Orion incorporates a more feasible pathway for the progressive research development testing and evaluation of the pulsed nuclear space propulsion system. Photofission through the application of an ultra-intense laser enables a much more controllable and scalable nuclear yield. The energy source for the ultra-intense laser is derived from a first stage liquid hydrogen and liquid oxygen chemical propulsion system. A portion of the thermal/kinetic energy of the rocket propulsive fluid is converted to electrical energy through a magneto-hydrodynamic generator with cryogenic propellant densification for facilitating the integral superconducting magnets. Fundamental analysis of Project New Orion demonstrates the capacity to impart a meaningful velocity increment through ultra-intense laser derived photofission on a small spacecraft.展开更多
Gas spark gap is widely used in any pulsed power system as the key element which directly determines its repetitive performance and output characteristics. Among many factors of threeelectrode gas spark gap, backgroun...Gas spark gap is widely used in any pulsed power system as the key element which directly determines its repetitive performance and output characteristics. Among many factors of threeelectrode gas spark gap, background pressure is of much importance in determining the gap performance parameters such as the delay and jitter, and relevant studies have been rarely performed. A magneto-hydrodynamic model of the arc in gas spark gap is built and the effects of background pressure on the arc characteristics are discussed in this paper. It is demonstrated that a higher background pressure may result in radial compression of the arc column, a higher arc voltage, and a lower declination rate of arc resistance in the first quarter cycle. Relevant simulation data would be helpful for the optimization of the design of gas spark gap.展开更多
In this work,several key scaling laws of the quasi-static magnetic compression of field reversed configuration(FRC)plasma(Spencer et al 1983 Phys.Fluids 261564)are amended from a series of two-dimensional FRC MHD equi...In this work,several key scaling laws of the quasi-static magnetic compression of field reversed configuration(FRC)plasma(Spencer et al 1983 Phys.Fluids 261564)are amended from a series of two-dimensional FRC MHD equilibriums numerically obtained using the Grad–Shafranov equation solver NIMEQ.Based on the new scaling for the elongation and the magnetic fields at the separatrix and the wall,the empirically stable limits for the compression ratio,the fusion gain,and the neutron yield are evaluated,which may serve as a more accurate estimate for the upper ceiling of performance from the magnetic compression of FRC plasma as a potential fusion energy as well as neutron source devices.展开更多
In this contemporary study,theoritical investigation of nanofluidic model is thought-out.Two-dimensional nanomaterials based mixed flow is considered here.Convective solar radiative heat transport properties have been...In this contemporary study,theoritical investigation of nanofluidic model is thought-out.Two-dimensional nanomaterials based mixed flow is considered here.Convective solar radiative heat transport properties have been investigated over a nonlinearly stretched wall in the presence of magneto-hydrodynamic(MHD),by innovative application of semi analytical“optimal homotopy asymptotic method(OHAM)”.OHAM does not require any discretization,linearization and small parameter assumption.OHAM describes extremely precise 1^(st)/2^(nd) order solutions without the need of computing further higher order terms,therefore,fast convergence is observed.Nanofluidic governing model is transformed into system of ordinary differential equations(ODEs)by exploitation of similarity transformation.To study the significance of radiation parameter alongwith thermophoresis parameter,a semi analytical solver is applied to the transformed system.In this work,Brownianmotion,influence ofmagnetic field,Lewis number,Prandtl number,Eckert number and Biot number have investigated on velocity,temperature and nanoparticle concentration profiles.The study provides sufficient number of graphical representations to demonstrate the inspiration of mentioned parameters.展开更多
文摘Natural convection flow in enclosure has different applications such as room ventilation, heat exchangers, the cooling system of a building etc. The Finite-Element method based on the Galerkin weighted residual approach is used to solve two-dimensional governing mass, momentum and energy-equations for natural convection flow in the presence of a magnetic field on a roof top with semi-circular heater. In the enclosure the horizontal lower wall was heated, the vertical two walls were adiabatic, inside the semi-circular heater, the wavy top wall cooled. The parameters Rayleigh number, Hartmann number and Prandtl number are considered. The effects of the Hartmann number and Rayleigh number on the streamlines, isotherms, velocity profiles and average Nusselt number are examined graphically. The local Nusselt number and the average Nusselt number of the heated portion of the enclosure with the semi-circular heater are presented in this paper. Finally, for the validation of the existing work, the current results are compared with published results and the auspicious agreement is achieved.
基金supported by the National Natural Science Foundation of China(12371123).
文摘Let(u,B)be a strong solution of the magneto-hydrodynamic system on three dimensional torus T^(3).In this note,using the properties of the curl operator,we show that‖(▽×(u-B),▽×(u+B))(·,t)‖L^(1)+1/2v‖(u-B,u+B)(·,t)‖_(L^(2))^(2)is decreasing in time t as long as the solution(u,B)(·,t)exists,where∇×w means the curl of the vector function w,and v>0 is the viscosity coefficient.
基金National Natural Science Foundation of China (Grant No. 11771284).
文摘We investigate the Cauchy problem for the 3D magneto-hydrodynamics equations with only horizontal dissipation for the small initial data. With the help of the dissipation in the horizontal direction and the structure of the system, we analyze the properties of the decay of the solution and apply these decay properties to get the global regularity of the solution. In the process, we mainly use the frequency decomposition in Green's function method and energy method.
基金supported via funding from Prince Sattam bin Abdulaziz University project number(PSAU/2025/R/1446)。
文摘This work investigates thermal enhancement in fluid flow over a nonlinear stretching sheet.The thickness of the sheet is variable and the flow of the fluid is affected by solar radiation energy with Thompson and Troian slip effects.The flow is magnetized by applying a magnetic field in the normal direction to the flow system.Moreover,thermal transport is controlled by incorporating the Cattaneo-Christov heat fluid model into the flow problem.The governing equations,initially framed in their dimensional form,are meticulously transformed into a dimensionless framework to simplify the analysis.These dimensionless equations are then solved using the homotopy analysis method(HAM).It is observed in this study that upsurges in the stagnation parameter,critical shear rate and velocity slip factor augment the velocity distribution while reducing the thermal profiles.The velocity distribution deteriorates while the thermal profiles are amplified with expansions in the magnetic factor and power law index.The thermal distribution also increases with rising Prandtl number and radiation factor.Augmentation of the power-law index,velocity slip parameter,critical shear rate,magnetic factor and stagnation parameter leads to an increased Nusselt number.The modeled problem is validated by comparing the current results with established work for different values of nonlinear stretching factor n in terms of the drag force and thermal flow rate at η=0,and a good agreement is observed between the current and established results.
文摘The present exploration is conducted to describe the motion of viscous fluid embedded in squeezed channel under the applied magnetics effects.The processes of heat and mass transport incorporate the temperature-dependent binary chemical reaction with modified Arrhenius theory of activation energy function which is not yet disclosed for squeezing flow mechanism.The flow,heat and mass regime are exposed to be governed via dimensionless,highly non-linear,ordinary differential equations (ODEs) under no-slip walls boundary conditions.A well-tempered analytical convergent procedure is adopted for the solutions of boundary value problem.A detailed study is accounted through graphs in the form of flow velocity field,temperature and fluid concentration distributions for various emerging parameters of enormous interest.Skin-friction,Nusselt and Sherwood numbers have been acquired and disclosed through plots.The results indicate that fluid temperature follows an increasing trend with dominant dimensionless reaction rate σ and activation energy parameter E.However,an increment in σ and E parameters is found to decline in fluid concentration.The current study arises numerous engineering and industrial processes including polymer industry,compression and injection shaping,lubrication system,formation of paper sheets,thin fiber,molding of plastic sheets.In the area of chemical engineering,geothermal engineering,cooling of nuclear reacting,nuclear or chemical system,bimolecular reactions,biochemical process and electrically conducting polymeric flows can be controlled by utilizing magnetic fields.Motivated by such applications,the proposed study has been developed.
基金supported by US DoE Contract No.DE-AC02-09-CH11466by the National Magnetic Confinement Fusion Science Program of China(No.2011GB105003)by the US DOE SBIR grant#94307S10-Ⅱ
文摘This paper introduces the notion of Tokamak Magneto-Hydrodynamics （TMHD）, which explicitly reflects the anisotropy of a high temperature tokamak plasma. The set of TMHD equations is formulated for simulation of macroscopic plasma dynamics and disruptions in tokamaks. Free from the Courant restriction on the time step, this set of equations is adequate to plasma dynamics with realistic parameters of high performance plasmas and does not require any extension of the MHD plasma model. At the same time, TMHD requires the use of magnetic field aligned numerical grids. Examples of their use in 2-dimensional cases of tokamak equilibria and dynamics of the wall touching kink mode are presented. For the 3-dimensional case of an ergodic magnetic field, this paper introduces the reference magnetic coordinates as a practical algorithm for generating adaptive grids for TMHD.
文摘This article proves the logarithmically improved Serrin＇s criterion for solutions of the 3D generalized magneto-hydrodynamic equations in terms of the gradient of the velocity field, which can be regarded as improvement of results in [10] （Luo Y W. On the regularity of generalized MHD equations. J Math Anal Appl, 2010, 365： 806-808） and [18] （Zhang Z J. Remarks on the regularity criteria for generalized MHD equations. J Math Anal Appl, 2011, 375：799 802）.
文摘This paper concerns the Cauchy problem of the 3D generalized incompressible magneto-hydrodynamic(GMHD) equations. By using the Fourier localization argument and the Littlewood-Paley theory, we get local well-posedness results of the GMHD equations with large initial data(u0, b0) belonging to the critical Fourier-Besov-Morrey spaces FN^1-2α+3/p'+λ/pp,λ,q(R^3) Moreover, stability of global solutions is also discussed.
基金Project supported by the National Natural Science Foundation of China （Grant No. 11071159） and the College Science Research Project of Inner Mongolia, China （Grant No. NJzy08180）.
文摘The approximate solution of the magneto-hydrodynamic （MHD） boundary layer flow over a nonlinear stretching sheet is obtained by combining the Lie symmetry method with the homotopy perturbation method. The approximate solution is tabulated, plotted for the values of various parameters and compared with the known solutions. It is found that the approximate solution agrees very well with the known numerical solutions, showing the reliability and validity of the present work.
基金supported by the National Natural Science Foundation of China(No.90716025)。
文摘This paper presents an integrated research scheme for vector deflection and energy extraction in a gas plasma jet under Magneto-Hydrodynamic(MHD)control.A MHDcontrolled thrust-vector test rig was used to conduct the experimental research.A gas plasma was obtained by injecting ionization seeds of Cs2CO3 into the combustion chamber via artificially forced ionization.The effects of the gas temperature and ionization seed mass fraction on the plasma jet deflection and energy extraction were experimentally verified under an applied magnetic field.The experimental results were analyzed theoretically.The results showed that the deflection amplitude of the gas plasma jet and the extracted voltage signal intensity increased with increasing gas temperature and the ionization seed mass fraction.The extracted dynamic voltage signals proved that the ionization seeds of Cs2CO3 induced gas ionization at 1173 K.The experiment verified that it is feasible to simultaneously achieve jet deflection and extract energy under the action of an external magnetic field.
基金Project supported by the National Natural Science Foundation of China(Nos.12250410244,11872151)the Jiangsu Province Education Development Special Project-2022 for Double First-ClassSchool Talent Start-up Fund of China(No.2022r109)the Longshan Scholar Program of Jiangsu Province of China。
文摘The work is devoted to the fractional characterization of time-dependent coupled convection-diffusion systems arising in magnetohydrodynamics(MHD)flows.The time derivative is expressed by means of Caputo’s fractional derivative concept,while the model is solved via the full-spectral method(FSM)and the semi-spectral scheme(SSS).The FSM is based on the operational matrices of derivatives constructed by using higher-order orthogonal polynomials and collocation techniques.The SSS is developed by discretizing the time variable,and the space domain is collocated by using equal points.A detailed comparative analysis is made through graphs for various parameters and tables with existing literature.The contour graphs are made to show the behaviors of the velocity and magnetic fields.The proposed methods are reasonably efficient in examining the behavior of convection-diffusion equations arising in MHD flows,and the concept may be extended for variable order models arising in MHD flows.
基金Item Sponsored by the German Research Foundation (Deutsche Forschungsgemeinschaft) for the Research Training Group (Graduiertenkolleg) "Lorentz force Velocimetry and Lorentz Force Eddy Current Testing"
文摘The present work is an analysis on the ElectroMagnetic Lorentz Force Velocimetry(EM-LFV).This noncontact flow measurement technique is based on evaluating the Lorentz force generated by the interactions of an electrically conducting fluid with a localized magnetic field that is produced by electromagnets.Analytical and numerical calculations were carried out as a continuation of a previous work published by Thess et al.The objective is to establish the behavior of the Lorentz force as a function of the main geometric parameters considered in the studied geometry. Thus we present here the evolution of the Lorentz force induced in a translating cylindrical solid body and the coefficient of sensitivity of the flowmeter thanks to numerical simulations in respect with the main geometrical parameters of the problem.
文摘In this paper, phenomena of superposability and self superposability in hydrodynamics and magneto hydrodynamics have been discussed. One of the most important applications of superposability in hydrodynamics is the construction of exact analytic solution of the basic equation of fluid dynamics. Kapur and Bhatia have given a simple idea that if two velocity vectors have self superposable and mutually superposable motion then sum or difference of these two is self superposable and vice versa and if each of the vector is superposable on the third then their sum and difference are also superposable on the third. For superposability in magneto-hydrodynamics many mathematicians like Ram Moorthy, Ram Ballabh, Mittal, Kapur & Bhatia and Gold & Krazyblocki have defined it in various ways, especially Kapur & Bhatia generalized the well-known work on superposability by Ram Ballabh to the case of viscous incompressible electrically conducting fluids in the presence of magnetic field. We found the relationship of two basic vectors for two important curvilinear coordinate systems for their use in our work. We’ve found the equations of div, curl and grad for a unit vector in parabolic cylinder coordinates and ellipsoidal coordinates for further use.
文摘Based on results obtained from the study for MHD （magneto-hydrodynamics） of advective accretion disk, which are applied to real source showing typical values for CBS （close binary star-system）, it will investigate on self-structuring in the disk under the impact of the distribution of leading parameters （density, velocity ...）. The paper is considering the problem of development of the corona and will analyze the process of interaction of the plasma with the magnetic field in connection to support for the instabilities.
文摘In this article, we present accurate analytical solutions for boundary layer flow and heat transfer of an incompressible and electrically conducting viscoelastic fluid over a linearly stretching surface subject to a transverse uniform magnetic field using the homotopy analysis method （HAM） for two general types of non-isothermal boundary conditions. In addition, we demonstrate that the previously reported analytical solutions for the temperature field given in terms of Kummer＇s function do not converge at the boundary. We provide a graphical and numerical demonstration of the convergence of the HAM solutions and tabulate the effects of various parameters on the skin friction coefficient and wall heat transfer.
文摘Project New Orion entails a pulsed nuclear space propulsion system that utilizes photofission through the implementation of an ultra-intense laser. The historical origins derive from the endeavors of Project Orion, which utilized thermonuclear devices to impart a considerable velocity increment on the respective spacecraft. The shear magnitude of Project Orion significantly detracts from the likelihood of progressive research development testing and evaluation. Project New Orion incorporates a more feasible pathway for the progressive research development testing and evaluation of the pulsed nuclear space propulsion system. Photofission through the application of an ultra-intense laser enables a much more controllable and scalable nuclear yield. The energy source for the ultra-intense laser is derived from a first stage liquid hydrogen and liquid oxygen chemical propulsion system. A portion of the thermal/kinetic energy of the rocket propulsive fluid is converted to electrical energy through a magneto-hydrodynamic generator with cryogenic propellant densification for facilitating the integral superconducting magnets. Fundamental analysis of Project New Orion demonstrates the capacity to impart a meaningful velocity increment through ultra-intense laser derived photofission on a small spacecraft.
基金supported by National Natural Science Foundation of China (No. 51807184)
文摘Gas spark gap is widely used in any pulsed power system as the key element which directly determines its repetitive performance and output characteristics. Among many factors of threeelectrode gas spark gap, background pressure is of much importance in determining the gap performance parameters such as the delay and jitter, and relevant studies have been rarely performed. A magneto-hydrodynamic model of the arc in gas spark gap is built and the effects of background pressure on the arc characteristics are discussed in this paper. It is demonstrated that a higher background pressure may result in radial compression of the arc column, a higher arc voltage, and a lower declination rate of arc resistance in the first quarter cycle. Relevant simulation data would be helpful for the optimization of the design of gas spark gap.
基金supported by the National Magnetic Confinement Fusion Program of China (No. 2017YFE0301805)National Natural Science Foundation of China (No. 51821005)+3 种基金the Fundamental Research Funds for the Central Universities at Huazhong University of Science and Technology (No. 2019kfy XJJS193)the U.S. Department of Energy (Nos. DE-FG02-86ER53218 and DE-SC0018001)the supports from the NIMROD teamthe support from the Chinese Government Scholarship.
文摘In this work,several key scaling laws of the quasi-static magnetic compression of field reversed configuration(FRC)plasma(Spencer et al 1983 Phys.Fluids 261564)are amended from a series of two-dimensional FRC MHD equilibriums numerically obtained using the Grad–Shafranov equation solver NIMEQ.Based on the new scaling for the elongation and the magnetic fields at the separatrix and the wall,the empirically stable limits for the compression ratio,the fusion gain,and the neutron yield are evaluated,which may serve as a more accurate estimate for the upper ceiling of performance from the magnetic compression of FRC plasma as a potential fusion energy as well as neutron source devices.
文摘In this contemporary study,theoritical investigation of nanofluidic model is thought-out.Two-dimensional nanomaterials based mixed flow is considered here.Convective solar radiative heat transport properties have been investigated over a nonlinearly stretched wall in the presence of magneto-hydrodynamic(MHD),by innovative application of semi analytical“optimal homotopy asymptotic method(OHAM)”.OHAM does not require any discretization,linearization and small parameter assumption.OHAM describes extremely precise 1^(st)/2^(nd) order solutions without the need of computing further higher order terms,therefore,fast convergence is observed.Nanofluidic governing model is transformed into system of ordinary differential equations(ODEs)by exploitation of similarity transformation.To study the significance of radiation parameter alongwith thermophoresis parameter,a semi analytical solver is applied to the transformed system.In this work,Brownianmotion,influence ofmagnetic field,Lewis number,Prandtl number,Eckert number and Biot number have investigated on velocity,temperature and nanoparticle concentration profiles.The study provides sufficient number of graphical representations to demonstrate the inspiration of mentioned parameters.
