Numerical simulation of compressible fluid-particle flows in multimaterial Lagrangian hydrodynamics framework

In the numerical simulation of multimaterial flows, Lagrangian method was applied widely, and fluid-particle multiphase flows phenomenon often existed when elastic-plastic material was impacted intensively. Most of the previous studies about the fluid-particle flows in Lagrangian hydrodynamics framework only focused on the dilute flow. It is very necessary to establish a Lagrangian-Lagrangian coupling numerical simulation framework, which is suitable for both multimaterial and dense particle flows in engineering applications. In present study, a numerical model, in which both continuous fluid phase and dispersed particle phase are discretized in Lagrangian frameworks, is developed. In this model, the effect of particle volume fraction, collision force among particles, interaction and coupling between fluid and particle phases are all considered based on the physical meanings. Therefore it is well-suited to complex multiphase flows including transition between dense and dilute particles flows, and material interfaces and free boundaries in multimaterial flows can be solved spontaneously. The relevant numerical technology and approach are proposed and derived, including fixed background mesh, higher order interpolation function, discetezation of coupling source terms and so on. The above numerical model and approach are integrated to a multimaterial staggered-grid elastic-plastic Lagrangian hydrodynamics code. A series of tests, including single particle transport, shock-induced dense particles bed, and explosive dispersal of solid particles, are used to validate the model. The numerical results show excellent agreement with theoretical solutions or experimental measurements, providing confidence in the proposed numerical model and methods.