Numerical Simulation Of Liquid-solid Flow Characteristics In Porous Media Based On Lattice Boltzmann Method

The phenomenon of liquid-solid flow in porous media widely exists in the fields of chemistry,agriculture,biology and industry.Especially in the petroleum industry,the migration and deposition of small particles in rock pores reduce the permeability of the reservoir and affect the normal exploitation of crude oil.Therefore,the study of liquid-solid flow characteristics in porous media is helpful to reveal the migration and deposition mechanism of suspended particles,which can provide a basis for oil exploration and improvement of recovery rate.The numerical simulation of fluid and suspended particle flow in three-dimensional porous media is carried out based on lattice Boltzmann method(LBM).The finite size particle method is used to construct fixed and suspended particles in porous media,and the interactions between the particles and fluid is handled by the Half-way bounce back format.The dimensional analysis method is introduced to carry out the conversion between the lattice unit and the actual physical unit.Combined with the analytical method for the kinetic theory of granular flow,the interactions between particles,particles and pore walls are explored.The results of numerical simulations reflect the influence of local particle-particle interactions on the macroscopic flow characteristics in porous media.The results show that the increase of the liquid velocity reduces the migration time of suspended particles in the porous medium and prevents the particles from being deposited downward under the influence of gravity.The time to reach stability can be shortened by46.3%.Reynolds stress,granular temperature and particle axial velocity are increased accordingly,while the deposition rate and particle residence time are reduced.With the increment of liquid viscosity,the granular temperature is first reduced and then increased,the deposition rate and the particle residence time are first enhanced and then declined,and the particles tend to move along the main flow channel of the fluid.The Reynolds stress is lowered,and the particle contact force is first increased and then decreased.The inlet pressure and outlet pressure are improved and lessened,respectively.As the porosity is diminished,the granular temperature is rose,the contact between the particles and the pore wall is added,and the deposition rate is increased first and then decreased.The lower the porosity is,the more frequent the axial distribution of the particle axial velocity,the Reynolds stress and the particle contact force are,and the greater the variations of the pressure are.With the enhancement of the particle density,the particle residence time and granular temperature are first decreased and then increased,while deposition rate is raised first and then reduced.The mean Reynolds stress and the normal contact force of particles is first lessened and then boosted.The maximum axial velocity of the particles at the particle density of 2150 kg/m~3 can reach more than 5 times that at the particle density of 1720 kg/m~3 and 2580 kg/m~3.As the particle diameter is increased,the collisions between particles are reduced,the deposition rate is lowered,and the granular temperature is improved.The particle residence time is first decreased and then increased.