Study On Taylor-couette Flow Characteristics Under Temperature Gradient

Taylor-Couette(T-C)flow is a classical research device in the field of fluid mechanics because of its simple structure but rich flow pattern.The traditional research is concentrated in the field of Newtonian's fluid,for non Newtonian fluids,especially for viscoelastic fluids,there are few studies,especially considering the study of temperature gradient.On the basis of T-C flow,this paper uses numerical software Open FOAM to simulate the flow of different fluids under different working conditions,the pure natural convection,isothermal condition and non isothermal T-C flow in the coaxial cylinder gap of Newtonian fluid and viscoelastic fluid are studied.The effects of rotational speed(Re),temperature gradient(Ra)and elastic stress(Wi)on the flow state were also analyzed.First,the control equations used in the numerical simulation process are determined according to the different boundary conditions for each fluid,and the Boussinesq hypothesis is introduced in the solution of the temperature difference effect.The dimensionless parameters are selected to dimensionless control equations,and the dimensionless control equations and dimensionless numbers are obtained and compiled in Open FOAM.Then,the verification process of the solver is introduced in detail.The critical Re number range of T-C flow is determined.All viscoelastic fluids are simulated by FENE-P model.Secondly,in the numerical simulation of natural convection in the coaxial cylinders,according to the control variables of the fluid,the Newtonian fluid under different Ra numbers,the viscoelastic fluid expansion under different Ra numbers and the Wi number are studied.The effect of temperature and elastic stress in the flow is determined by analyzing the distribution of velocity,temperature and conformation tensor.The critical Ra number of flow transitions is obtained and the effect of elasticity for flow stability was analyzed.Thirdly,the T-C flow states of Newtonian fluids with different Reynolds numbers and viscoelastic fluids at different Wi numbers or Reynolds numbers were studied.The flow states corresponding to different Reynolds numbers were obtained and the elasticity effect were analyzed.Comparing this results with the existing conclusions further proves the reliability of the simulation results.Finally,the T-C flow with non isothermal process is studied.For Newtonian fluid,the control variables are Ra and Re.For viscoelastic fluids,the control parameters are Wi numbers,Ra numbers and Re.The influence of temperature,speed and elasticity on flow is studied by changing the control variables of each fluid.