Numerical Simulation Of The Solid Particle Motion And Collision In The Couette Flow

Lattice Boltzmann simulation of collisions between circular particles suspension in Couette flow is studied in this paper.Firstly, multiple-relaxation-time based lattice Boltzmann and Direct Forcing/ Fictitious Domain method is established for simulation of particle two-phase flow by introducing fictitious domain method based on direct forcing model to lattice Boltzmann method. The advantage of this method is avoiding remesh while particles are moving in fluid by using Lagrangian mesh in particels and Eulerian grid in fluid, separately. Moreover, it is not necessary to explicitly calculate the force and torque acting on particles while sloving the motions of particles.Secondly, uniform flow past a fixed elliptical cylinder is numerical simulated by adopting multiple-relaxation-time based lattice Boltzmann and Direct Forcing/ Fictitious Domain method. This method is validated by comparing the simulation results with such of commercial software FLUENT. And then vortex-shedding patterns are studied while the elliptical cylinder moving harmonically in the flow direction, which will influnced by the amplitude and frequency of the harmonic motion. The code is further validated by comparing the above results with those by using dynamic mesh of commercial software FLUENT.Thirdly, the same method is utilized to investigate the movement and collision of particles in regular distribution which suspeneded in Couette flow. When there are 128 particles and the shear velocity is relatively small which equals to 0.1 m/s, the particles collision number is also very small. Furthermore, when the shear velocity increases to 0.2m/s and 0.3m/s, the particles collision number increases accordingly. And it is also found that when the shear velocity is large enough, the particles collision number will not change a lot. To investigate the influence of the Reynolds number and the density of particles on the particles collision number, in the following simualtions, all physical quantities are nondimensionalized and the shear velocity is set to be 0.08. It is found that when the number of particles is 128, the particles collision number does not show obvious regular changes. Generally, the particles collision number is inversely correlated with the Reynolds number. However, the particles collision number changes more irregularly while varing the density of particles. When the number of particles increases to 256, the particles collision number decreases with increasing of the Raynolds number and the density of particles.Finally, it is investigated that the movement and collision of particles in irregular distribution which suspeneded in Couette flow. Similarly, when the number of particles is 128, the particles collision number does not show obvious regular changes. Generally, the particles collision number is inversely correlated with the Reynolds number and the density of particles. But when the number of particles is 256, obviously, the particles collision number increases with decreasing of the Raynolds number and the density of particles. Moreover, comparing with the particles in regular distribution, the particles in irregular distribution collide each other much earlier, whenever the number of particles is 128 or 256.