Effect of the Coulomb and dielectric forces on the onset of Rayleigh-Bénard convection  

库仑力和介电力对瑞利-贝纳德对流的影响

作　　者：Zhonglin Du Pedro A.Vázquez Jian Wu 杜中林;Pedro A.Vázquez;吴健

机构地区：[1]School of Energy Science and Engineering,Harbin Institute of Technology,Harbin,150001,China [2]Heilongjiang Key Laboratory of Micro-and Nano-scale Fluid Flow and Heat Transfer,Harbin,150001,China [3]Departamento de Física Aplicada III,ETSII,Universidad de Sevilla,Sevilla,41092,Spain

出　　处：《Acta Mechanica Sinica》2024年第6期64-77,共14页力学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.12172110);the Fundamental Research Funds for Central Universities,China(Grant No.AUGA9803500921).

摘　　要：In this paper,the effect of Coulomb and dielectric forces on the onset of Rayleigh-Bénard convection(RBC)in a dielectric liquid layer contained between two parallel electrode plates has been numerically investigated.Two different operating conditions have been considered in electrohydrodynamic(EHD)conduction:ohmic and saturation,and variations in the physical properties of the dielectric fluid with temperature.The electric equations and the state equations based on the Boussinesq approximation are integrated in the framework of OpenFOAM buoyantBoussinesqPimpleFoam program.The results show that in the ohmic regime,the combined effect of Coulomb and dielectric forces promotes the onset of RBC flow,while in the saturation state,the inhibition of RBC flow by Coulomb force is more significant.The value of the critical Rayleigh number Ra decreases with increasing electric Reynolds number ReE in the ohmic regime,whereas in the saturation state,the critical Ra increases with increasing ReE.In the saturation regime,the flow field always has a steady flow in the range of parameters considered.However,the onset of the RBC flow promoted by the dielectric force is more pronounced in the ohmic state.Due to the presence of the dielectric force,the flow field exhibits periodic oscillatory flow at low electric Reynolds numbers for the range of parameters considered.在本文中,我们用数值模拟研究了库仑力和介电力对两个平行电极板之间介电液体层中Rayleigh-Bénard对流(RBC)的影响,考虑了电传导的两种不同工作状态:欧姆和饱和以及介电液体物理性质随温度的变化.电方程和基于Boussinesq近似的状态方程被集成到OpenFOAM的buoyantBoussinesqPimpleFoam程序框架中.结果表明,在欧姆状态下,库仑力和介电力的共同作用促进了RBC的流动,而在饱和状态下,库仑力对RBC流动的抑制作用更为明显.在欧姆状态下,临界瑞利数Ra的值随着电雷诺数ReE增大而减小,而在饱和状态下,临界瑞利数Ra则随着ReE增大而增大.在饱和状态下,流场在所考虑的参数范围内始终是稳定流动.然而,在欧姆状态下,介电力促进RBC的起始流动得更为明显.由于介电力的存在,在所考虑的参数范围内,流场在低电雷诺数时呈现周期性振荡流动.

关 键 词：EHD conduction Dielectric force Rayleigh-Bénard convection OPENFOAM 

分 类 号：O35[理学—流体力学]