Numerically investigation was carried out for turbulent magnetohydrodynamics natural convection in a square enclosure.The vertical walls are maintained isothermal at different temperatures and the horizontal walls are...Numerically investigation was carried out for turbulent magnetohydrodynamics natural convection in a square enclosure.The vertical walls are maintained isothermal at different temperatures and the horizontal walls are adiabatic. Non linear goveming equations for the fluid flow and heat transfer are solved by finite volume method.The computations are carded out for Rayleigh number 107,Hartmann numbers from 0 to 800 and Prandtl number 0.01(sodium).It is observed that as the Hartmarm number increases the stratification of the temperature field in the interior reduces,and the thermal boundary layers at the two side walls begin to diminish and the isotherms become almost parallel to the vertical walls which indicates that natural convection heat transfer has been changed to conduction mode.展开更多
The effects of result from the substitution of the classical Fourier law by the non-classical Maxwell-Cattaneo law on the Rayleigh-Bénard Magneto-convection in an electrically conducting micropolar fluid is studi...The effects of result from the substitution of the classical Fourier law by the non-classical Maxwell-Cattaneo law on the Rayleigh-Bénard Magneto-convection in an electrically conducting micropolar fluid is studied using the Galerkin technique. The eigenvalue is obtained for free-free, rigid-free and rigid-rigid velocity boundary combinations with isothermal or adiabatic temperature on the spin-vanishing boundaries. The influences of various micropolar fluid parameters are analyzed on the onset of convection. The classical approach predicts an infinite speed for the propagation of heat. The present non-classical theory involves a wave type heat transport (SECOND SOUND) and does not suffer from the physically unacceptable drawback of infinite heat propagation speed. It is found that the results are noteworthy at short times and the critical eigenvalues are less than the classical ones.展开更多
Galileo mission detected the magnetic anomalies originated from Galilean moons.These anomalies are likely generated in the moons' interiors,under the influence of a strong ambient Jovian field.Among various possib...Galileo mission detected the magnetic anomalies originated from Galilean moons.These anomalies are likely generated in the moons' interiors,under the influence of a strong ambient Jovian field.Among various possible generation mechanisms of the anomalies,we focus on magneto-convection and dynamos in the interiors via numerical simulation.To mimic the electromagnetic environment of the moons,we introduce in our numerical model an external uniform magnetic field B0 with a fixed orientation but varying field strength.Our results show that a finite B0 can substantially alter the dynamo processes inside the core.When the ambient field strength B0 increases to approximately 40% of the field generated by the pure dynamo action,the convective state in the core changes significantly:the convective flow decreases by 80% in magnitude,but the differential rotation becomes stronger in much of the fluid layer,leading to a stronger field generated in the core.The field morphologies inside the core tend to align with the ambient field,while the flow patterns show the symmetry-breaking effect under the influence of B0.Furthermore,the generated field tends to be temporally more stable.展开更多
文摘Numerically investigation was carried out for turbulent magnetohydrodynamics natural convection in a square enclosure.The vertical walls are maintained isothermal at different temperatures and the horizontal walls are adiabatic. Non linear goveming equations for the fluid flow and heat transfer are solved by finite volume method.The computations are carded out for Rayleigh number 107,Hartmann numbers from 0 to 800 and Prandtl number 0.01(sodium).It is observed that as the Hartmarm number increases the stratification of the temperature field in the interior reduces,and the thermal boundary layers at the two side walls begin to diminish and the isotherms become almost parallel to the vertical walls which indicates that natural convection heat transfer has been changed to conduction mode.
文摘The effects of result from the substitution of the classical Fourier law by the non-classical Maxwell-Cattaneo law on the Rayleigh-Bénard Magneto-convection in an electrically conducting micropolar fluid is studied using the Galerkin technique. The eigenvalue is obtained for free-free, rigid-free and rigid-rigid velocity boundary combinations with isothermal or adiabatic temperature on the spin-vanishing boundaries. The influences of various micropolar fluid parameters are analyzed on the onset of convection. The classical approach predicts an infinite speed for the propagation of heat. The present non-classical theory involves a wave type heat transport (SECOND SOUND) and does not suffer from the physically unacceptable drawback of infinite heat propagation speed. It is found that the results are noteworthy at short times and the critical eigenvalues are less than the classical ones.
基金supported by National Natural Science Foundation of China (Grant No. 40328006)
文摘Galileo mission detected the magnetic anomalies originated from Galilean moons.These anomalies are likely generated in the moons' interiors,under the influence of a strong ambient Jovian field.Among various possible generation mechanisms of the anomalies,we focus on magneto-convection and dynamos in the interiors via numerical simulation.To mimic the electromagnetic environment of the moons,we introduce in our numerical model an external uniform magnetic field B0 with a fixed orientation but varying field strength.Our results show that a finite B0 can substantially alter the dynamo processes inside the core.When the ambient field strength B0 increases to approximately 40% of the field generated by the pure dynamo action,the convective state in the core changes significantly:the convective flow decreases by 80% in magnitude,but the differential rotation becomes stronger in much of the fluid layer,leading to a stronger field generated in the core.The field morphologies inside the core tend to align with the ambient field,while the flow patterns show the symmetry-breaking effect under the influence of B0.Furthermore,the generated field tends to be temporally more stable.
