Patterns for Parallel Software Design

6.2. 6.2 Adaptive 3D Grid-Based Eulerian (Gasdynamic) Program

In collaboration with Miguel Angel Palomera-Pérez

6.2.1. Problem Analysis

6.2.1.1. Problem Statement

Yguazú is a parallel, 3D, adaptive grid code developed to solve gasdynamic equations¹ based on Van Leer's 'flux vector splitting' algorithm. It uses a fast, semi-implicit method for solving a system of rate equations for atomic/ionic and molecular species [RNV00]. The application was originally developed on a shared memory platform using Fortran and OpenMP as its programming environment. It integrates a 3D Euler (gasdynamic) system of equations and a series of rate equations. The system of equations is written as [RNV00]:

In this equation, the variables U, F, G, H and S are expressed in vector terms as [RNV00]:

In all these equations, the vector (u,v,w) represents the three components of flow velocity in the directions (x,y,z), ρ is density, P is pressure, T is temperature, and n₁...n_R are the number densities of the atomic/ionic and molecular species with masses m₁...m_R and charges z₁...z_R. The specific heat at constant volume (C_v) has a complex behavior, which for the purposes of this application is approximated ...