微极液体在两个多孔圆盘间的MHD流动及其热传导

MHD Flow and Heat Transfer of a Micropolar Fluid Between Two Porous Disks

两个平行的无限大多孔圆盘,圆盘表面有均匀注入时,数值地研究圆盘间不可压缩导电微极流体,在横向外加磁场作用下的轴对称稳定层流.运用von Krmn的相似变换,将非线性运动的控制方程转化为无量纲形式.使用基于有限差分格式的算法,在相应的边界条件下,求解简化后耦合的常微分方程组.讨论Reynolds数、磁场参数、微极参数和Prandtl数,对流动速度和温度分布的影响.在特殊情况下,所得结果与已有文献的工作有着很好的一致性.研究表明,圆盘表面的传热率随着Rynolds数、磁场参数和Prandtl数的增加而增加;剪切应力随着注入的增加而减少,但它随着外部磁场的加强而增加.和Newton流体相比较,微极流体的剪切应力因素较弱,有利于聚合体加工过程中流动和温度的控制.

A numerical study of axisymmetric steady laminar incompressible flow of an electrically conducting micropolar fluid between two infinite parallel porous disks with constant uniform injection through the surface of the disks was carried out when the fluid was subjected to an external transverse magnetic field. The governing nonlinear equations of motion were trans- formed in dimensionless form through von Karman＇ s similarity transformation. An algorithm based on finite difference scheme was used to solve the reduced coupled ordinary differential equations with associated boundary conditions. Effects of Reynolds number, magnetic parame- ter, micropolar parameter and Prandtl number on the flow velocity and temperature distribution were discussed. Results compare well with the previously published work for special case. Investigations predict that the heat transfer rate at the surfaces of the disks increased with an increase in the values of Reynolds number, magnetic parameter and Prandtl number. The shear stresses decreased by increasing the injection while these stresses increased with increased applied magnetic field. The shear stress factor was lower for micropolar fluids than for Newtonian fluids, which may be beneficial in flow and thermal control of polymeric processing.