Parallel computation of rising bubbles using the lattice Boltzmann method on workstation cluster

Abstract

This chapter develops and parallelizes the three-dimensional two-phase flow simulation code based on the two component two-phase lattice Boltzmann method, in which two distribution functions are used to represent two phases using the message-passing interface (MPI) library. Parallel computations are performed on a workstation cluster composed of different types of workstations. Rising bubbles and their coalescence in a static fluid are simulated as one of the fundamental two-phase flow phenomena. Two bubbles go up due to the gravity and the vortex is formed around the bubbles. The lower bubble goes up faster since the upward flow is established in the wake of the upper bubble. The shape of the lower bubble is not much deformed in comparison with the upper bubble, though the rising velocity is larger. The efficiency of parallel computations is discussed. The simulation region was divided into small regions by the domain decomposition method. The appropriate region size for each workstation was automatically obtained at the beginning of the parallel computations, and efficient computations were performed. The workstation cluster consists of four COMPAQ au600 (Alpha 21164, 600MHz) workstations and four COMPAQ XP1000 (Alpha 21264, 500MHz) workstations. These workstations are connected through 100BaseTx (100 Mb/s) network and a switching hub.