一种全耦合多相流分析的并行计算方法

A PARALELL ANALYSIS METHOD FOR FULL COUPLED MULTIPHACE FLOW 1)

研究了孔隙介质中热、水和汽流全耦合分析的并行计算方法．模型中采用了考虑毛细压力关系的修正有效应力概念，并考虑了相变和潜热传递．基本变量为位移、毛细压力、汽压和温度．并行程序是在国家高性能计算中心（北京）的曙光１０００Ａ上借助ＰＶＭ（ＰａｒａｌｅｌＶｉｒｔｕａｌＭａｃｈｉｎｅ）软件系统实现的。

In this paper, we consider a full coupled multi phase problem involving heat and mass transfer in deforming porous media. The mathematical model consists of balance equations of mass, linear momentum and energy and of the appropriate constitutive equations. The chosen macroscopic field variables are temperature, capillary pressure, gas pressure and displacement. The gas phase is considered to be an ideal gas composed of dry air and vapour, which are regarded as two miscible species. The model makes further use of a modified effective stress concept together with the capillary pressure relationship. Phase change is taken into account as well as heat transfer though conduction and convection and latent heat transfer (evaporation condensation). Discretization of the non linear governing equations is carried out by means of finite elements in space and finite differeces in time. A multi frontal parallel method in conjunction with a Newton Raphson procedure is developed to solve above problem. The given domain of the problem is descretized into a finite number of subregions or subdomains. Multi fronts are used to assemble and eliminate internal variable concurrently in every subregion. The contributions for interface equations are obtained from the frontal operating arrays when every wavefront comes to the boundary of its own subregion. Interface equations are solved to obtain the values of the boundary nodes of the subregion. Once the values of the boundary nodes have been determined, the values within each subregion may be determined by a back substitution routines of the multi frontal procedures independently. This method has advantages shch as numbering of the finite element mesh in an arbitrary manner, simple programming organisation, smaller core requirements and shorten computation times. The parallel program is developed on Dawning Tiangchao (1000A) parallel computer. The PVM(Parallel Virtual Machine) system is used to handle communications among processors. Numerical examples are given to demonstrated the speedup and efficiency of this method.