Direct Numerical Simulation For Particulate Flows With Distributed Lagrange Multiplier/fictitious Domain Method

The numerical simulation is an important aspect for the development of multiphase flow study, which requires more advanced and precise numerical method. Because direct numerical simulation can precisely give us both the micro- and macro- information, thereafter, it is more attracting nowadays. In this paper, particles' descent in stable fluid and suspended & fluidized by fluid was simulated by distributed Lagrange multiplier/fictitious domain method (DLM/FD).The result shows that the DLM/FD method is an effective way to explore particulate flows. It exactly reflects the couple force between the particles and fluid. The particle's rotation near the wall is simulated, which fits the result from experiment. The simulation also shows the effect of the wall. The particle seems to have an equilibrium position near the center between two walls which are not too wide. When the slip velocity between particles and fluid is large enough, vortexes will form and left, which leads to the oscillations of particles. Fluidized by flows, particles will suspend. And the height of particle is related to the speed of flows. The result of many particles' descent and fluidization shows that particles which have different densities will gather at certain height.It is demonstrated that the micro structure of particulate flows can be achieved by direct numerical simulation; furthermore, the better understanding for the constitutive rules can be expected.