A comparative study of four solid ratio calculation methods for immersed moving boundary-lattice Boltzmann method
The immersed moving boundary(IMB)can be implemented into the lattice Boltzmann method(LBM)to guarantee non-slip condition at moving particle boundaries,in which fluid-solid coupling can be realized.This IMB-LBM coupled model requires calculating the solid ratio.The calculation method of solid ratio has an effect on the accuracy and efficiency of fluid-solid coupling calculation.Four common methods for calculating solid ratio are Monte Carlo method(MCM),unit decomposition method(UDM),approxi-mate polygon method(APM)and closed boundary method(CBM).In this paper,the specific algorithms of the four methods are described and their calculation accuracy and efficiency are compared.And their time consumption in fluid-solid coupling calculation is compared through modeling a multi-particle settlement flu-id-solid coupling example by disk discontinuous deformation analysis(DDDA)and lattice Boltzmann method(LBM)coupling model.The results reveal that:1)CBM has no error,while the relative error of MCM and UDM is about 1％when the number of random points is 1000 and the number of sub-units is 100.The error of APM is less than 0.44％when the particle diameter is 10 times larger than the lattice length;2)The accuracy and time consumption of MCM and UDM are respectively correlated with the number of ran-dom points and sub-units,and their calculations are more time-consuming than both APM and CBM;3)In calculation efficiency,APM＞CBM＞UDM＞MCM,the time consumption of CBM is a little more than APM,and the time consumption of a single calculation in MCM is 2 orders of magnitude more than that of APM.The time consumption of a single calculation in MCM is 1 orders of magnitude more than that of UDM.These conclusions can provide a reference for the optimization of the calculation method of solid ratio in IMB-LBM coupled model
万方数据
维普
