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CivilComp Proceedings
ISSN 17593433 CCP: 90
PROCEEDINGS OF THE FIRST INTERNATIONAL CONFERENCE ON PARALLEL, DISTRIBUTED AND GRID COMPUTING FOR ENGINEERING Edited by:
Paper 32
Parallel Moving Particle Calculations using the Immersed Boundary Method Z. Wang, J. Fan and K. Cen
State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, P.R. China Z. Wang, J. Fan, K. Cen, "Parallel Moving Particle Calculations using the Immersed Boundary Method", in , (Editors), "Proceedings of the First International Conference on Parallel, Distributed and Grid Computing for Engineering", CivilComp Press, Stirlingshire, UK, Paper 32, 2009. doi:10.4203/ccp.90.32
Keywords: immersed boundary method, parallel calculation, particle moving, multiphase flow, numerical simulation, particle sediment.
Summary
Gassolid multiphase flow exists widely in nature and in industry. In the numerical study of multiphase flow, some new numerical techniques for the simulation of multiphase flow are proposed which contain the volume effect of the particles. The immersed boundary method based on the uniform Cartesian grids has been applied for the simulation of multiphase system [1,2]. Due to the great computational cost, parallel schemes are necessary, and some schemes are proposed recently [3,4]. The parallel efficiency is high when the particles are distributed in the flow field uniformly because the particles (or Lagrangian points) are calculated on each processor are almost the same. And for the case with nonuniform distribution of the particle phase such as the fluidized bed, the workload for some processors are very heavy while it is quite light for some other processors. The cost for each time step is determined by the processor with the heaviest workload. To increase the computational speed, the workload on each processor should be redistributed. The processors with light workloads help the processors with heavy workloads to finish the particlerelated calculation. Based on this spirit, a parallel scheme is proposed in present paper to balance the workload of the particlerelated operations on each processor when the immersed boundary method is applied for the simulation of the multiphase system.
In order to validate the parallel scheme proposed in present paper for workload balance, three cases are conducted. The first case is the simulation of a solid particle settling in a rectangular channel. The good agreement of the particle settling velocity between the present result and the experimental results of Mordant and Pinton [5] validates the accuracy of the present algorithm. The second case is that one processor is full of 66 particles and the other processors do not contain any particle. Very high parallel efficiency is obtained when two and three processors are applied which are 0.966 and 0.91, respectively. A greater number of the processors used for parallel calculation leads to a lower parallel efficiency. The third case is the simulation of the sedimentation of 660 particles in a closed box. This case shows the ability of present parallel scheme in the calculation of a large number particles. In this case, the entire parallel efficiency is higher than 0.9. References
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