In a direct numerical simulation of gas-particle flow with meshless method,if the integral is carried out with common background integral cells numerical pressure fluctuation occurs.It results in unsuccessful computations.We analyze the reason and develope a solution strategy.It is used in the simulation of one particle dropping.Reasonable results are obtained.It shows that the new strategy avoids pressure fluctuation.

In numerical simulation using meshless method,it usually concerns with searching nodes that are needed.In dealing with complex problems,there must be a great number of nodes distributed in computational domain.If traditional Node-Searching method is used here, it will be a burdensome task for the computer.So this paper proposes a new numerical arithmetic,Domain-Dividing method which means that the domain can be divided into several subdomains.Therefore,one can search some corresponding subdomains but not the entire domain for the neccessory nodes. It adopts the Node-Searching arithmetic to simulate the ideal flow over a cylinder,and shows that with the increase of the nodes in domain,the computational time of meshless method gets longer than that of finite element method,however compared with meshless method using conventional Node-Searching method,the arithmetic proposed here can spare much more time for searching nodes.

Drag force is a key parameter in the analysis of gas-solid flow,especially in dense vertical flows,and is important in numerical simulation of the gas-solid flow.To describe the cluster phenomena and their effects on drag force, a new model of gas-solid drag force is developed under the consideration of cluster effects using the energy minimization concept.Compared with the existing drag models,the new one can reasonably describe the interaction between gas and particle phase,and avoid the error caused by the inaccurate experimental coefficients.It can improve the accuracy of the simulation of dense gas-solid two-phase flow greatly.