This work is concerned with applying the fractional calculus approach to the magnetohydrodynamic （MHD） pipe flow of a fractional generalized Burgers＇ fluid in a porous space by using modified Darcy＇s relationship....This work is concerned with applying the fractional calculus approach to the magnetohydrodynamic （MHD） pipe flow of a fractional generalized Burgers＇ fluid in a porous space by using modified Darcy＇s relationship. The fluid is electrically conducting in the presence of a constant applied magnetic field in the transverse direction. Exact solution for the velocity distribution is developed with the help of Fourier transform for fractional calculus. The solutions for a Navier-Stokes, second grade, Maxwell, Oldroyd-B and Burgers＇ fluids appear as the limiting cases of the present analysis.展开更多
In this paper,the mechanism of thermal energy transport in swirling flow of the Maxwell nanofluid induced by a stretchable rotating cylinder is studied.The rotation of the cylinder is kept constant in order to avoid t...In this paper,the mechanism of thermal energy transport in swirling flow of the Maxwell nanofluid induced by a stretchable rotating cylinder is studied.The rotation of the cylinder is kept constant in order to avoid the induced axially secondary flow.Further,the novel features of heat generation/absorption,thermal radiation,and Joule heating are studied to control the rate of heat transfer.The effects of Brownian and thermophoretic forces exerted by the Maxwell nanofluid to the transport of thermal energy are investigated by utilizing an effective model for the nanofluid proposed by Buongiorno.The whole physical problem of fluid flow and thermal energy transport is modelled in the form of partial differential equations(PDEs)and transformed into nonlinear ordinary differential equations(ODEs)with the help of the suitable flow ansatz.Numerically acquired results through the technique bvp4c are reported graphically with physical explanation.Graphical analysis reveals that there is higher transport of heat energy in the Maxwell nanoliquid for a constant wall temperature(CWT)as compared with the prescribed surface temperature(PST).Both thermophoretic and Brownian forces enhance the thermal energy transport in the flowing Maxwell nanofluid.Moreover,the temperature distribution increases with increasing values of the radiation parameter and the Eckert number.It is also noted that an increase in Reynolds number reduces the penetration depth,and as a result the flow and transport of energy occur only near the surface of the cylinder.展开更多
A nanofluid is composed of a base fluid component and nanoparticles, in which the nanoparticles are dispersed in the base fluid. The addition of nanoparticles into a base fluid can remarkably improve the thermal condu...A nanofluid is composed of a base fluid component and nanoparticles, in which the nanoparticles are dispersed in the base fluid. The addition of nanoparticles into a base fluid can remarkably improve the thermal conductivity of the nanofluid, and such an increment of thermal conductivity can play an important role in improving the heat transfer rate of the base fluid. Further, the dynamics of non-Newtonian fluids along with nanoparticles is quite interesting with numerous industrial applications. The present predominately predictive modeling studies the flow of the viscoelastic Oldroyd-B fluid over a rotating disk in the presence of nanoparticles. A progressive amendment in the heat and concentration equations is made by exploiting the Cattaneo-Christov heat and mass flux expressions. The characteristic of the Lorentz force due to the magnetic field applied normal to the disk is studied. The Buongiorno model together with the Cattaneo-Christov theory is implemented in the Oldroyd-B nanofluid flow to investigate the heat and mass transport mechanism. This theory predicts the characteristics of the fluid thermal and solutal relaxation time on the boundary layer flow. The von K′arm′an similarity functions are utilized to convert the partial differential equations(PDEs) into ordinary differential equations(ODEs). A homotopic approach for obtaining the analytical solutions to the governing nonlinear problem is carried out. The graphical results are obtained for the velocity field, temperature, and concentration distributions. Comparisons are made for a limiting case between the numerical and analytical solutions, and the results are found in good agreement. The results reveal that the thermal and solutal relaxation time parameters diminish the temperature and concentration distributions, respectively. The axial flow decreases in the downward direction for higher values of the retardation time parameter. The impact of the thermophoresis parameter boosts the temperature distribution.展开更多
A new mathematical model is presented to study the heat and mass transfer characteristics of magnetohydrodynamic(MHD) Maxwell fluid flow over a convectively heated stretchable rotating disk. To regulate the fluid temp...A new mathematical model is presented to study the heat and mass transfer characteristics of magnetohydrodynamic(MHD) Maxwell fluid flow over a convectively heated stretchable rotating disk. To regulate the fluid temperature at the surface, a simple isothermal model of homogeneous-heterogeneous reactions is employed. The impact of nonlinear thermal radiative heat flux on thermal transport features is studied. The transformed nonlinear system of ordinary differential equations is solved numerically with an efficient method, namely, the Runge-Kutta-Felberg fourth-order and fifth-order(RKF45)integration scheme using the MAPLE software. Achieved results are validated with previous studies in an excellent way. Major outcomes reveal that the magnetic flux reduces the velocity components in the radial, angular, and axial directions, and enhances the fluid temperature. Also, the presence of radiative heat flux is to raise the temperature of fluid. Further, the strength of homogeneous-heterogeneous reactions is useful to diminish the concentration of reaction.展开更多
This paper deals with the magnetohydrodynamic （MHD） flow of an Oldroyd 8-constant fluid in a porous medium when no-slip condition is no longer valid. Modified Darcy＇s law is used in the flow modelling. The non-line...This paper deals with the magnetohydrodynamic （MHD） flow of an Oldroyd 8-constant fluid in a porous medium when no-slip condition is no longer valid. Modified Darcy＇s law is used in the flow modelling. The non-linear differential equation with non-linear boundary conditions is solved numerically using finite difference scheme in combination with an iterative technique. Numerical results are obtained for the Couette, Poiseuille and generalized Couette flows. The effects of slip parameters on the velocity profile are discussed.展开更多
The study of non-axisymmetric Homann stagnation-point flow of Walter’s B nanofluid along with magnetohydrodynamic(MHD) and non-linear Rosseland thermal radiation over a cylindrical disk in the existence of the time-i...The study of non-axisymmetric Homann stagnation-point flow of Walter’s B nanofluid along with magnetohydrodynamic(MHD) and non-linear Rosseland thermal radiation over a cylindrical disk in the existence of the time-independent free stream is considered. Moreover, the notable impacts of thermophoresis and Brownian motion are analyzed by Buongiorno’s model. The momentum, energy, and concentration equations are converted into the dimensionless coupled ordinary differential equations via similarity transformations, which are later numerically solved by altering the values of the pertinent parameters. The numerical and asymptotic solutions for the large shear-to-strain rate ratio γ =a/bfor the parameters of the displacement thicknesses and the wall-shear stress are computed by perturbative expansion and analyzed. Furthermore, the technique bvp4c in MATLAB is deployed as an efficient method to analyze the calculations for the non-dimensional velocities, temperature, displacement thickness, and concentration profiles. It is observed that the two-dimensional displacement thickness parameters α andβ are reduced due to the viscoelasticity and magnetic field effects. Moreover, when the shear-to-strain rate ratio approaches infinity, α is closer to its asymptotic value, while βand the three-dimensional displacement thickness parameter δ1 show the opposite trend.The outcomes of the viscoelasticity and the magnetic field on the skin friction are also determined. It is concluded that ■ reaches its asymptotic behavior when the shearto-strain rate ratio approaches infinity. Meanwhile, ■ shows different results.展开更多
The heat transfer of Homann flow in the stagnation region of the Al2 O3-Cu/water hybrid nanofluid is investigated by adopting the Tiwari-Das model over a cylindrical disk.The effects of the nanoparticle shape,the visc...The heat transfer of Homann flow in the stagnation region of the Al2 O3-Cu/water hybrid nanofluid is investigated by adopting the Tiwari-Das model over a cylindrical disk.The effects of the nanoparticle shape,the viscous dissipation,and the nonlinear radiation are considered.The governing equations are obtained by using similarity transformations,and the numerical outcomes for the flow and the temperature field are noted by bvp4 c on MATLAB.The numerical solutions of the flow field are compared with the asymptotic behaviors of large shear-to-strain-rate ratio.The effects of variations of parameters involved are inspected for both nanofluid and hybrid nanofluid flows,temperature profiles,local Nusselt numbers,and skin frictions.It is concluded that the velocity and temperature fields in the hybrid nanophase function more rapidly than those in the nanofluid phase.展开更多
This research paper analyzes the transport of thermal and solutal energy in the Maxwell nanofluid flow induced above the disk which is rotating with a constant angular velocity.The significant features of thermal and ...This research paper analyzes the transport of thermal and solutal energy in the Maxwell nanofluid flow induced above the disk which is rotating with a constant angular velocity.The significant features of thermal and solutal relaxation times of fluids are studied with a Cattaneo-Christov double diffusion theory rather than the classical Fourier’s and Fick’s laws.A novel idea of a Buongiorno nanofluid model together with the Cattaneo-Christov theory is introduced for the first time for the Maxwell fluid flow over a rotating disk.Additionally,the thermal and solutal distributions are controlled with the impacts of heat source and chemical reaction.The classical von Karman similarities are used to acquire the non-linear system of ordinary differential equations(ODEs).The analytical series solution to the governing ODEs is obtained with the well-known homotopy analysis method(HAM).The validation of results is provided with the published results by the comparison tables.The graphically presented outcomes for the physical problem reveal that the higher values of the stretching strength parameter enhance the radial velocity and decline the circumferential velocity.The increasing trend is noted for the axial velocity profile in the downward direction with the higher values of the stretching strength parameter.The higher values of the relaxation time parameters in the Cattaneo-Christov theory decrease the thermal and solutal energy transport in the flow of Maxwell nanoliquids.The higher rate of the heat transport is observed in the case of a larger thermophoretic force.展开更多
This work concerns with the exact solutions of magnetohydrodynamic（MHD）flow of generalized Burgers fluid describing the second Stokes problem. The modified Darcy law is taken into account. The related velocity distr...This work concerns with the exact solutions of magnetohydrodynamic（MHD）flow of generalized Burgers fluid describing the second Stokes problem. The modified Darcy law is taken into account. The related velocity distribution and shear stress are expressed as a combination of steady-state and transient solutions computed by means of integral transformations. The effects of various parameters on the flow field are investigated. The MHD flow results in reduction of velocity distribution and associated thickness of the boundary layer.展开更多
In an experiment carried out at the Prague Asterix Laser System at laser intensities relevant to shock ignition conditions(I>10^(16) W/cm^(2)),the heating and transport of hot electrons were studied by using severa...In an experiment carried out at the Prague Asterix Laser System at laser intensities relevant to shock ignition conditions(I>10^(16) W/cm^(2)),the heating and transport of hot electrons were studied by using several complementary diagnostics,i.e.,K_(α)time-resolved imaging,hard x-ray filtering(a bremsstrahlung cannon),and electron spectroscopy.Ablators with differing composition from low Z(parylene N)to high Z(nickel)were used in multilayer planar targets to produce plasmas with different coronal temperature and collisionality and modify the conditions of hot-electron generation.The variety of available diagnostics allowed full characterization of the population of hot electrons,retrieving their conversion efficiency,time generation and duration,temperature,and angular divergence.The obtained results are shown to be consistent with those from detailed simulations and similar inertial confinement fusion experiments.Based on the measured data,the advantages,reliability,and complementarity of the experimental diagnostics are discussed.展开更多
The present research article is devoted to studying the characteristics of Cattaneo-Christov heat and mass fluxes in the Maxwell nanofluid flow caused by a stretching sheet with the magnetic field properties.The Maxwe...The present research article is devoted to studying the characteristics of Cattaneo-Christov heat and mass fluxes in the Maxwell nanofluid flow caused by a stretching sheet with the magnetic field properties.The Maxwell nanofluid is investigated with the impact of the Lorentz force to examine the consequence of a magnetic field on the flow characteristics and the transport of energy.The heat and mass transport mechanisms in the current physical model are analyzed with the modified versions of Fourier’s and Fick’s laws,respectively.Additionally,the well-known Buongiorno model for the nanofluids is first introduced together with the Cattaneo-Christov heat and mass fluxes during the transient motion of the Maxwell fluid.The governing partial differential equations(PDEs)for the flow and energy transport phenomena are obtained by using the Maxwell model and the Cattaneo-Christov theory in addition to the laws of conservation.Appropriate transformations are used to convert the PDEs into a system of nonlinear ordinary differential equations(ODEs).The homotopic solution methodology is applied to the nonlinear differential system for an analytic solution.The results for the time relaxation parameter in the flow,thermal energy,and mass transport equations are discussed graphically.It is noted that higher values of the thermal and solutal relaxation time parameters in the Cattaneo-Christov heat and mass fluxes decline the thermal and concentration fields of the nanofluid.Further,larger values of the thermophoretic force enhance the heat and mass transport in the nanoliquid.Moreover,the Brownian motion of the nanoparticles declines the concentration field and increases the temperature field.The validation of the results is assured with the help of numerical tabular data for the surface velocity gradient.展开更多
This paper investigates the boundary layer flow of the Maxwell fluid around a stretchable horizontal rotating cylinder under the influence of a transverse magnetic field.The constitutive flow equations for the current...This paper investigates the boundary layer flow of the Maxwell fluid around a stretchable horizontal rotating cylinder under the influence of a transverse magnetic field.The constitutive flow equations for the current physical problem are modeled and analyzed for the first time in the literature.The torsional motion of the cylinder is considered with the constant azimuthal velocity E.The partial differential equations(PDEs)governing the torsional motion of the Maxwell fluid together with energy transport are simplified with the boundary layer concept.The current analysis is valid only for a certain range of the positive Reynolds numbers.However,for very large Reynolds numbers,the flow becomes turbulent.Thus,the governing similarity equations are simplified through suitable transformations for the analysis of the large Reynolds numbers.The numerical simulations for the flow,heat,and mass transport phenomena are carried out in view of the bvp4c scheme in MATLAB.The outcomes reveal that the velocity decays exponentially faster and reduces for higher values of the Reynolds numbers and the flow penetrates shallower into the free stream fluid.It is also noted that the phenomenon of stress relaxation,described by the Deborah number,causes to decline the flow fields and enhance the thermal and solutal energy transport during the fluid motion.The penetration depth decreases for the transport of heat and mass in the fluid with the higher Reynolds numbers.An excellent validation of the numerical results is assured through tabular data with the existing literature.展开更多
This article reports the simultaneous properties of variable conductivity and chemical reaction in stagnation point flow of magneto Maxwell nanofluid.The Buongiorno’s theory has been established to picture the induce...This article reports the simultaneous properties of variable conductivity and chemical reaction in stagnation point flow of magneto Maxwell nanofluid.The Buongiorno’s theory has been established to picture the inducement of Brownian and thermophrotic diffusions effects.Additionally,the aspect of heat sink/source is reported.The homotopic analysis method(HAM)has been worked out for the solution of nonlinear ODEs.The behavior of inferential variables on the velocity,temperature,concentration and local Nusselt number for Maxwell nanofluid are sketched and discussed.The attained outcomes specify that both the temperature and concentration of Maxwell fluid display analogous behavior,while the depiction of Brownian motion is quite conflicting on both temperature and concentration fields.It is further noted that the influence of variable thermal conductivity on temperature field is similar to that of Brownian motion parameter.Moreover,for the confirmation of our study comparison tables are reported.展开更多
We report results and modelling of an experiment performed at the Target Area West Vulcan laser facility,aimed at investigating laser±plasma interaction in conditions that are of interest for the shock ignition s...We report results and modelling of an experiment performed at the Target Area West Vulcan laser facility,aimed at investigating laser±plasma interaction in conditions that are of interest for the shock ignition scheme in inertial confinement fusion(ICF),that is,laser intensity higher than 10^(16) W/cm^(2) impinging on a hot(T>1 keV),inhomogeneous and long scalelength pre-formed plasma.Measurements show a significant stimulated Raman scattering(SRS)backscattering(;%-20%of laser energy)driven at low plasma densities and no signatures of two-plasmon decay(TPD)/SRS driven at the quarter critical density region.Results are satisfactorily reproduced by an analytical model accounting for the convective SRS growth in independent laser speckles,in conditions where the reflectivity is dominated by the contribution from the most intense speckles,where SRS becomes saturated.Analytical and kinetic simulations well reproduce the onset of SRS at low plasma densities in a regime strongly affected by non-linear Landau damping and by filamentation of the most intense laser speckles.The absence of TPD/SRS at higher densities is explained by pump depletion and plasma smoothing driven by filamentation.The prevalence of laser coupling in the low-density profile justifies the low temperature measured for hot electrons(7-12 keV),which is well reproduced by numerical simulations.展开更多
A developing application of laser-driven currents is the generation of magnetic fields of picosecond-nanosecond duration with magnitudes exceeding B=10 T.Single-loop and helical coil targets can direct laser-driven di...A developing application of laser-driven currents is the generation of magnetic fields of picosecond-nanosecond duration with magnitudes exceeding B=10 T.Single-loop and helical coil targets can direct laser-driven discharge currents along wires to generate spatially uniform,quasi-static magnetic fields on the millimetre scale.Here,we present proton deflectometry across two axes of a single-loop coil ranging from 1 to 2 mm in diameter.Comparison with proton tracking simulations shows that measured magnetic fields are the result of kiloampere currents in the coil and electric charges distributed around the coil target.Using this dual-axis platform for proton deflectometry,robust measurements can be made of the evolution of magnetic fields in a capacitor coil target.展开更多
文摘This work is concerned with applying the fractional calculus approach to the magnetohydrodynamic （MHD） pipe flow of a fractional generalized Burgers＇ fluid in a porous space by using modified Darcy＇s relationship. The fluid is electrically conducting in the presence of a constant applied magnetic field in the transverse direction. Exact solution for the velocity distribution is developed with the help of Fourier transform for fractional calculus. The solutions for a Navier-Stokes, second grade, Maxwell, Oldroyd-B and Burgers＇ fluids appear as the limiting cases of the present analysis.
文摘In this paper,the mechanism of thermal energy transport in swirling flow of the Maxwell nanofluid induced by a stretchable rotating cylinder is studied.The rotation of the cylinder is kept constant in order to avoid the induced axially secondary flow.Further,the novel features of heat generation/absorption,thermal radiation,and Joule heating are studied to control the rate of heat transfer.The effects of Brownian and thermophoretic forces exerted by the Maxwell nanofluid to the transport of thermal energy are investigated by utilizing an effective model for the nanofluid proposed by Buongiorno.The whole physical problem of fluid flow and thermal energy transport is modelled in the form of partial differential equations(PDEs)and transformed into nonlinear ordinary differential equations(ODEs)with the help of the suitable flow ansatz.Numerically acquired results through the technique bvp4c are reported graphically with physical explanation.Graphical analysis reveals that there is higher transport of heat energy in the Maxwell nanoliquid for a constant wall temperature(CWT)as compared with the prescribed surface temperature(PST).Both thermophoretic and Brownian forces enhance the thermal energy transport in the flowing Maxwell nanofluid.Moreover,the temperature distribution increases with increasing values of the radiation parameter and the Eckert number.It is also noted that an increase in Reynolds number reduces the penetration depth,and as a result the flow and transport of energy occur only near the surface of the cylinder.
文摘A nanofluid is composed of a base fluid component and nanoparticles, in which the nanoparticles are dispersed in the base fluid. The addition of nanoparticles into a base fluid can remarkably improve the thermal conductivity of the nanofluid, and such an increment of thermal conductivity can play an important role in improving the heat transfer rate of the base fluid. Further, the dynamics of non-Newtonian fluids along with nanoparticles is quite interesting with numerous industrial applications. The present predominately predictive modeling studies the flow of the viscoelastic Oldroyd-B fluid over a rotating disk in the presence of nanoparticles. A progressive amendment in the heat and concentration equations is made by exploiting the Cattaneo-Christov heat and mass flux expressions. The characteristic of the Lorentz force due to the magnetic field applied normal to the disk is studied. The Buongiorno model together with the Cattaneo-Christov theory is implemented in the Oldroyd-B nanofluid flow to investigate the heat and mass transport mechanism. This theory predicts the characteristics of the fluid thermal and solutal relaxation time on the boundary layer flow. The von K′arm′an similarity functions are utilized to convert the partial differential equations(PDEs) into ordinary differential equations(ODEs). A homotopic approach for obtaining the analytical solutions to the governing nonlinear problem is carried out. The graphical results are obtained for the velocity field, temperature, and concentration distributions. Comparisons are made for a limiting case between the numerical and analytical solutions, and the results are found in good agreement. The results reveal that the thermal and solutal relaxation time parameters diminish the temperature and concentration distributions, respectively. The axial flow decreases in the downward direction for higher values of the retardation time parameter. The impact of the thermophoresis parameter boosts the temperature distribution.
文摘A new mathematical model is presented to study the heat and mass transfer characteristics of magnetohydrodynamic(MHD) Maxwell fluid flow over a convectively heated stretchable rotating disk. To regulate the fluid temperature at the surface, a simple isothermal model of homogeneous-heterogeneous reactions is employed. The impact of nonlinear thermal radiative heat flux on thermal transport features is studied. The transformed nonlinear system of ordinary differential equations is solved numerically with an efficient method, namely, the Runge-Kutta-Felberg fourth-order and fifth-order(RKF45)integration scheme using the MAPLE software. Achieved results are validated with previous studies in an excellent way. Major outcomes reveal that the magnetic flux reduces the velocity components in the radial, angular, and axial directions, and enhances the fluid temperature. Also, the presence of radiative heat flux is to raise the temperature of fluid. Further, the strength of homogeneous-heterogeneous reactions is useful to diminish the concentration of reaction.
文摘This paper deals with the magnetohydrodynamic （MHD） flow of an Oldroyd 8-constant fluid in a porous medium when no-slip condition is no longer valid. Modified Darcy＇s law is used in the flow modelling. The non-linear differential equation with non-linear boundary conditions is solved numerically using finite difference scheme in combination with an iterative technique. Numerical results are obtained for the Couette, Poiseuille and generalized Couette flows. The effects of slip parameters on the velocity profile are discussed.
文摘The study of non-axisymmetric Homann stagnation-point flow of Walter’s B nanofluid along with magnetohydrodynamic(MHD) and non-linear Rosseland thermal radiation over a cylindrical disk in the existence of the time-independent free stream is considered. Moreover, the notable impacts of thermophoresis and Brownian motion are analyzed by Buongiorno’s model. The momentum, energy, and concentration equations are converted into the dimensionless coupled ordinary differential equations via similarity transformations, which are later numerically solved by altering the values of the pertinent parameters. The numerical and asymptotic solutions for the large shear-to-strain rate ratio γ =a/bfor the parameters of the displacement thicknesses and the wall-shear stress are computed by perturbative expansion and analyzed. Furthermore, the technique bvp4c in MATLAB is deployed as an efficient method to analyze the calculations for the non-dimensional velocities, temperature, displacement thickness, and concentration profiles. It is observed that the two-dimensional displacement thickness parameters α andβ are reduced due to the viscoelasticity and magnetic field effects. Moreover, when the shear-to-strain rate ratio approaches infinity, α is closer to its asymptotic value, while βand the three-dimensional displacement thickness parameter δ1 show the opposite trend.The outcomes of the viscoelasticity and the magnetic field on the skin friction are also determined. It is concluded that ■ reaches its asymptotic behavior when the shearto-strain rate ratio approaches infinity. Meanwhile, ■ shows different results.
文摘The heat transfer of Homann flow in the stagnation region of the Al2 O3-Cu/water hybrid nanofluid is investigated by adopting the Tiwari-Das model over a cylindrical disk.The effects of the nanoparticle shape,the viscous dissipation,and the nonlinear radiation are considered.The governing equations are obtained by using similarity transformations,and the numerical outcomes for the flow and the temperature field are noted by bvp4 c on MATLAB.The numerical solutions of the flow field are compared with the asymptotic behaviors of large shear-to-strain-rate ratio.The effects of variations of parameters involved are inspected for both nanofluid and hybrid nanofluid flows,temperature profiles,local Nusselt numbers,and skin frictions.It is concluded that the velocity and temperature fields in the hybrid nanophase function more rapidly than those in the nanofluid phase.
文摘This research paper analyzes the transport of thermal and solutal energy in the Maxwell nanofluid flow induced above the disk which is rotating with a constant angular velocity.The significant features of thermal and solutal relaxation times of fluids are studied with a Cattaneo-Christov double diffusion theory rather than the classical Fourier’s and Fick’s laws.A novel idea of a Buongiorno nanofluid model together with the Cattaneo-Christov theory is introduced for the first time for the Maxwell fluid flow over a rotating disk.Additionally,the thermal and solutal distributions are controlled with the impacts of heat source and chemical reaction.The classical von Karman similarities are used to acquire the non-linear system of ordinary differential equations(ODEs).The analytical series solution to the governing ODEs is obtained with the well-known homotopy analysis method(HAM).The validation of results is provided with the published results by the comparison tables.The graphically presented outcomes for the physical problem reveal that the higher values of the stretching strength parameter enhance the radial velocity and decline the circumferential velocity.The increasing trend is noted for the axial velocity profile in the downward direction with the higher values of the stretching strength parameter.The higher values of the relaxation time parameters in the Cattaneo-Christov theory decrease the thermal and solutal energy transport in the flow of Maxwell nanoliquids.The higher rate of the heat transport is observed in the case of a larger thermophoretic force.
文摘This work concerns with the exact solutions of magnetohydrodynamic（MHD）flow of generalized Burgers fluid describing the second Stokes problem. The modified Darcy law is taken into account. The related velocity distribution and shear stress are expressed as a combination of steady-state and transient solutions computed by means of integral transformations. The effects of various parameters on the flow field are investigated. The MHD flow results in reduction of velocity distribution and associated thickness of the boundary layer.
基金This work was carried out within the framework of the EUROfusion Consortium,funded by the European Union via the Euratom Research and Training Programme(Grant No.101052200-EUROfusion)Views and opinions expressed are however those of the authors only and do not necessarily reflect those of the European Union or the European Commission.Neither the European Union nor the European Commission can be held responsible for them.The involved teams have operated within the framework of the Enabling Research Project:Grant No.ENR-IFE.01.CEA“Advancing shock ignition for direct-drive inertial fusion.”The work was also supported by the Natural Sciences and Engineering Research Council of Canada(Grant No.RGPIN-2019-05013)+5 种基金The authors acknowledge support of the PALS Infrastructure within the MŠMT(MEYS)project Grant No.LM2023068Staff members of the PALS Research Center appreciate financial support(Grant No.LM2023068)from the Czech Ministry of Education,Youth and Sports facilitating operation of the PALS facilityThe work of JIHT RAS team was supported by the Ministry of Science and Higher Education of the Russian Federation(State Assignment No.075-01129-23-00)The work at NRMU MEPhI was supported by the Ministry of Science and Higher Education of the Russian Federation(Agreement No.075-15-2021-1361)This project has received funding from the CNR funded Italian research Network ELI-Italy(D.M.No.63108.08.2016)This work was funded by United Kingdom EPSRC Grants No.EP/P026796/1 and No.EP/L01663X/1.The results presented in this paper are based on work carried out between September 2018 and December 2021.
文摘In an experiment carried out at the Prague Asterix Laser System at laser intensities relevant to shock ignition conditions(I>10^(16) W/cm^(2)),the heating and transport of hot electrons were studied by using several complementary diagnostics,i.e.,K_(α)time-resolved imaging,hard x-ray filtering(a bremsstrahlung cannon),and electron spectroscopy.Ablators with differing composition from low Z(parylene N)to high Z(nickel)were used in multilayer planar targets to produce plasmas with different coronal temperature and collisionality and modify the conditions of hot-electron generation.The variety of available diagnostics allowed full characterization of the population of hot electrons,retrieving their conversion efficiency,time generation and duration,temperature,and angular divergence.The obtained results are shown to be consistent with those from detailed simulations and similar inertial confinement fusion experiments.Based on the measured data,the advantages,reliability,and complementarity of the experimental diagnostics are discussed.
文摘The present research article is devoted to studying the characteristics of Cattaneo-Christov heat and mass fluxes in the Maxwell nanofluid flow caused by a stretching sheet with the magnetic field properties.The Maxwell nanofluid is investigated with the impact of the Lorentz force to examine the consequence of a magnetic field on the flow characteristics and the transport of energy.The heat and mass transport mechanisms in the current physical model are analyzed with the modified versions of Fourier’s and Fick’s laws,respectively.Additionally,the well-known Buongiorno model for the nanofluids is first introduced together with the Cattaneo-Christov heat and mass fluxes during the transient motion of the Maxwell fluid.The governing partial differential equations(PDEs)for the flow and energy transport phenomena are obtained by using the Maxwell model and the Cattaneo-Christov theory in addition to the laws of conservation.Appropriate transformations are used to convert the PDEs into a system of nonlinear ordinary differential equations(ODEs).The homotopic solution methodology is applied to the nonlinear differential system for an analytic solution.The results for the time relaxation parameter in the flow,thermal energy,and mass transport equations are discussed graphically.It is noted that higher values of the thermal and solutal relaxation time parameters in the Cattaneo-Christov heat and mass fluxes decline the thermal and concentration fields of the nanofluid.Further,larger values of the thermophoretic force enhance the heat and mass transport in the nanoliquid.Moreover,the Brownian motion of the nanoparticles declines the concentration field and increases the temperature field.The validation of the results is assured with the help of numerical tabular data for the surface velocity gradient.
文摘This paper investigates the boundary layer flow of the Maxwell fluid around a stretchable horizontal rotating cylinder under the influence of a transverse magnetic field.The constitutive flow equations for the current physical problem are modeled and analyzed for the first time in the literature.The torsional motion of the cylinder is considered with the constant azimuthal velocity E.The partial differential equations(PDEs)governing the torsional motion of the Maxwell fluid together with energy transport are simplified with the boundary layer concept.The current analysis is valid only for a certain range of the positive Reynolds numbers.However,for very large Reynolds numbers,the flow becomes turbulent.Thus,the governing similarity equations are simplified through suitable transformations for the analysis of the large Reynolds numbers.The numerical simulations for the flow,heat,and mass transport phenomena are carried out in view of the bvp4c scheme in MATLAB.The outcomes reveal that the velocity decays exponentially faster and reduces for higher values of the Reynolds numbers and the flow penetrates shallower into the free stream fluid.It is also noted that the phenomenon of stress relaxation,described by the Deborah number,causes to decline the flow fields and enhance the thermal and solutal energy transport during the fluid motion.The penetration depth decreases for the transport of heat and mass in the fluid with the higher Reynolds numbers.An excellent validation of the numerical results is assured through tabular data with the existing literature.
基金the Deanship of Scientific Research at King Khalid University for funding this work through Research Groups Program under Grant number (R.G. P2. /26/40)
文摘This article reports the simultaneous properties of variable conductivity and chemical reaction in stagnation point flow of magneto Maxwell nanofluid.The Buongiorno’s theory has been established to picture the inducement of Brownian and thermophrotic diffusions effects.Additionally,the aspect of heat sink/source is reported.The homotopic analysis method(HAM)has been worked out for the solution of nonlinear ODEs.The behavior of inferential variables on the velocity,temperature,concentration and local Nusselt number for Maxwell nanofluid are sketched and discussed.The attained outcomes specify that both the temperature and concentration of Maxwell fluid display analogous behavior,while the depiction of Brownian motion is quite conflicting on both temperature and concentration fields.It is further noted that the influence of variable thermal conductivity on temperature field is similar to that of Brownian motion parameter.Moreover,for the confirmation of our study comparison tables are reported.
基金financial support from the LASERLAB-EUROPE Access to Research Infrastructure activity within the EC’s seventh Framework Program(Application No.18110033)carried out within the framework of the EUROfusion Enabling research projects AWP19-20-ENR-IFE19.CEA01 and AWP21-ENR-01-CEA-02+2 种基金funding from the Euratom research and training programme 20192020 and 2021-2025 under grant No.633053financial support from the CNR-funded Italian research Network ELI-Italy(D.M.No.63108.08.2016)the Czech Ministry of Education,Youth and Sports,project LTT17015。
文摘We report results and modelling of an experiment performed at the Target Area West Vulcan laser facility,aimed at investigating laser±plasma interaction in conditions that are of interest for the shock ignition scheme in inertial confinement fusion(ICF),that is,laser intensity higher than 10^(16) W/cm^(2) impinging on a hot(T>1 keV),inhomogeneous and long scalelength pre-formed plasma.Measurements show a significant stimulated Raman scattering(SRS)backscattering(;%-20%of laser energy)driven at low plasma densities and no signatures of two-plasmon decay(TPD)/SRS driven at the quarter critical density region.Results are satisfactorily reproduced by an analytical model accounting for the convective SRS growth in independent laser speckles,in conditions where the reflectivity is dominated by the contribution from the most intense speckles,where SRS becomes saturated.Analytical and kinetic simulations well reproduce the onset of SRS at low plasma densities in a regime strongly affected by non-linear Landau damping and by filamentation of the most intense laser speckles.The absence of TPD/SRS at higher densities is explained by pump depletion and plasma smoothing driven by filamentation.The prevalence of laser coupling in the low-density profile justifies the low temperature measured for hot electrons(7-12 keV),which is well reproduced by numerical simulations.
基金This paper was supported by the LLNL Academic Partnership in ICF,EPSRC grants EP/L01663X/1 and EP/L000644/1the Czech Republic MSMT targeted support of Large Infrastructures+1 种基金ELI Beamlines Project LQ1606 of the National Programme of Sustainability IIThe contribution of the JIHT RAS team was completed within the framework of the Russian Ministry state assignment for Science and Higher Education(topic#01201357846).
文摘A developing application of laser-driven currents is the generation of magnetic fields of picosecond-nanosecond duration with magnitudes exceeding B=10 T.Single-loop and helical coil targets can direct laser-driven discharge currents along wires to generate spatially uniform,quasi-static magnetic fields on the millimetre scale.Here,we present proton deflectometry across two axes of a single-loop coil ranging from 1 to 2 mm in diameter.Comparison with proton tracking simulations shows that measured magnetic fields are the result of kiloampere currents in the coil and electric charges distributed around the coil target.Using this dual-axis platform for proton deflectometry,robust measurements can be made of the evolution of magnetic fields in a capacitor coil target.
