Study Of Parallel Computing In Groundwater Contaminant Transport Simulation

Groundwater solute transport numerical simulation is an important method to reproduce and predict the characteristics of groundwater pollution transport.At present,with the rapid development of wireless monitoring network and remote sensing technology,numerical simulation of groundwater solute transport is moving towards large space-time scales and high precision trend.Using parallel computing to solve the bottleneck problem of large storage overhead and long time consuming is a proactive scientific proposition.This study focuses on how to parallelize the exist contaminant simulation program.The parallel algorithm and its realization of solute transport,parallel coupling of flow and solute transport,and practical applications were studied.The main contributions of this study are as follows:(1)Based on the domain decomposition method,a parallel algorithm for solute transport numerical simulation is proposed.The algorithm can ensure that the accuracy and convergence speed of solutions does not decrease with the increase of the number of domain areas.The parallel version MT3 DMS program(JMT3D)is realized based on the domain decomposition method,the data structure of JASMIN,and the ghost cells communication strategy.Through ideal examples and practical problems tests,it is verified that JMT3 D can get the same calculation accuracy as MT3 DMS.It can deal with tens of millions of scale grids computing,which reduces the average memory consumption by 96% on 46 processors.(2)By optimizing the flow-solute coupling calculation process of MODFLOWMT3 DMS,a mapping relationship on different spatial scales was established.The internal parallel coupling of the groundwater flow simulation program JOGFLOW and the solute transport program JMT3 D was realized.It solved the problem of large intermediate files and frequent I/O.The calculation process has been simplified.The output flowchart of results is improved and better meet the needs of users.(3)The performance analysis of different geological conditions,steady flow/ transient flow conditions,patch sizes,and problem scales were carried out.The results show that BiCGSTAB method achieves the shortest time consuming and higher speedup in most cases.It achieved 31.7 times speedup on 46 processors.The AMG method shows impressive scalability,achieves more than 100% efficiency on 112 and 224 processors.(4)The JMT3 D program was applied to the groundwater environmental impact assessment of a petrochemical project in Hami,Xinjiang province.In the prediction of possible environmental impacts of the coal chemical project,a reasonable plan was put forward,and reduced the time from 14.3 hours to 0.64 hours.It verified the ability of JMT3 D to deal with practical problems.