发展了用于不可压缩非等温非牛顿流模拟的广义特征线基分裂算法,推广了控制方程沿粒子特征线的离散格式,经典的特征线伽辽金法和时域的Crank—Nicolson离散格式可分别被归纳为离散格式的两个特例.为消除流体的不可压缩性导致的虚假数值振荡,采用压力稳定型分步算法.利用粘性系数关于等效应变速率的指数模型来模型化流体的非牛顿特性.平面Poisseuille流动和4:1平面收缩流动的数值模拟结果突出地显示了该方法处理不可压缩非等温非牛顿流动问题的有效性及良好性能.
A generalized scheme of the fractional step algorithm using characteristic based split (CBS) for numerical simulation of the incompressible non-isothermal non-Newtonian fluid flows is presented. The discretization scheme of the governing equations along the characteristics is generalized, so the classical characteristics Galerkin method and the classical Crank-Nicolson time discretization scheme can be classified as two special cases of the diseretization scheme developed respectively. Pressure stabilized fractional step algorithm is employed to remove the spurious numerical oscillations induced by the incompressibility of the fluid. The power law model of the viscosity in terms of the equivalent strain rate is used to model the non-Newtonian character of the fluid. Numerical results of the plane Poisseuille flow and the 4 : 1 plane contraction flow demonstrate and validate the performance and the capability of the proposed scheme.