Parallel Computation for Particle-Grid Hybrid Method

In this paper, parallel computational technology is used in the numerical analysis code of particle-grid hybrid method. Particle-grid hybrid method is a rising solution method to analyze two-phase flow problem. It has shown its ability in several two-dimensional simulations. However, when this method was used to predict the droplet entrainment ratio of annulus flow the calculation time was insufferable. When the droplet occurs in the gas core, the density field varying near the droplet is strenuous. The pressure correction equations are very hard to be convergence. Hence, the MPI (Message Passing Interface) library is chosen as the parallel technology to decrease the calculation time. The grid and particle calculation parts are paralleled, separately. Jacobi point iteration method and ADI (alternating direction implicit) combined with divide and flow line programming techniques for grid calculation are discussed. All the particles are divided into several groups depending on the processor number. Then several cases are set for testing the parallel efficiency. Generally, with four processors the efficiency is about 60%. If the processor number is more than four the parallel efficiency will decrease rapidly. This method can accelerate the hybrid method; however, it still needs improving. Finally, some droplet entrainment cases calculated by parallel code are summarized.Copyright © 2010 by ASME