| Electric(thermal)convection is one of the basic research topics of electrohydrodynamics,and it belongs to the multidisciplinary field of heat transfer,fluid mechanics,and electrodynamics.Electric field-based active flow control and enhanced heat transfer technology have received wide attention because of their unique advantages(no need for mechanical moving parts,low noise,fast response and low energy consumption,etc.).However,the theoretical basis of the electric-field-driven heat and mass transfer technique is that the mechanism of the electrohydrodynamics phenomenon has lagged behind.The core difficulties of this research are:(1)Strong nonlinear coupling of multiphysics(including electric field,flow field,temperature field,charge distribution field)(2)Multidisciplinary(including fluid mechanics,heat transfer,electromagnetics,electrochemical)Due to its own complexity,the theoretical analysis,experimental and numerical research of electrothermal convection problems are relatively scarce,which greatly hinders the development and application of electric field driven heat and mass transfer technology.At present,the theoretical research on this issue focuses on the linear stability analysis of simple geometric electrode system(such as double parallel plate,concentric cylinder,needle-plate structure,etc.).Most of the numerical results are based on the traditional solution of macroscopic control equations.Group methods(such as finite volume method and finite element method).It is particularly pointed out that there are not many researches on electric convection and electrothermal convection in China,and they have focused on the experimental research of electric field enhanced heat transfer,and there is less exploration of relevant mechanisms.In this paper,Mesoscopic lattice-Boltzmann method(LBM)is used to solve the electrothermal convection problem.As a mesoscopic evolution method,LBM is very suitable for solving the transient multi-field coupled transport process of electric(thermal)convection,can better restore the physical oscillation in the coupling process and eliminate non-physical oscillation,and capture the transient convection process.The linear and nonlinear stability of the critical point.Firstly,the lattice-Boltzmann model is constructed through theoretical analysis.Then,the two-dimensional convection numerical calculation is performed based on the separation-combination mechanism and three-dimensional electrothermal convection is gradually transitioned to the monopolar injection mechanism to draw a three-dimensional neutral stability curve.The details are as follows: According to the space dimension,the lattice Boltzmann model of the charge distribution field,potential field,flow field and temperature field is constructed using the D2Q9 or D3Q17 velocity discrete format;using the separation and combination mechanism,the numerical simulation work is performed based on the parallel plate-ring model.The influences of parameters such as electrical Rayleigh number T,dissociation rate constant W0,dimensionless mobility M,and aspect ratio 2R/L were studied.In addition,natural convection in two-dimensional circular cavity was also simulated.Simulation of coupled temperature difference buoyancy and potential difference Coulomb force,respectively,from the electric Rayleigh number T,Rayleigh number Ra,dimensionless mobility M,dimensionless charge diffusivity and Prandtl number Pr and other control parameters to study its three-dimensional The influence of electrothermal convection is given and specific measures for analysis and enhancement of mass transfer heat transfer are given.A linear stability analysis method is used to draw a three-dimensional neutral stability curve. |
PDF Full Text Request