Simulation Study On Flow Characteristics Of Particles In Micro-channel Based On CFD-DEM

Petroleum as a major strategic resources,which reasonable development and utilization is related to the vital survival and stability of China.However,at present,onshore developed geological reserves where oil deposit has been exhaustion with higher and higher water content in our Country,which makes the exploitation of low-permeable oil fields become the primary research tasks in the future.Most of low-permeable oil reservoir which have been exploited belong to a kind of low-porosity and low-permeable reservoir,A large number of gravel porous medium and micro cracks in micro scales which make the micro flow become the main flow way in displacement process.Thus,the traditional method is greatly limited by the experiment,the computer numerical simulation become an important means of liquidsolid two-phase flow simulation study.In this study,the liquid-solid flow in micro-channel,which has been simulated with the Euler-Lagrange method,And doing the liquid-particle and particle-grain four-way coupling calculation;Tracing particle tracks by discrete element model(DEM),with regarding particles as no size,and using Navier-Stokes method to solve;Fluid phase still as continuous phase,which will be solved by CFD method with k-turbulence model,and conform to the mass and momentum conservation equation.Establishing a 3D gravel porous medium model and a 2D micro-crack model to simulate,and researching effects of medium porosity,liquid viscosity,liquid velocity on liquid-solid two-phase flow in the micro-channel,through analyzing the regulation of instantaneous velocity,particle trajectory and particle distribution of fluid velocity in the channel at a certain moment,fluid velocity vector chart,residence time,retention rate,temperature and contact force and other aspects,it is concluded that the flow characteristics of liquid-solid two phases in micro-channel.In conclusions,with the increase of porosity particles flow will tend to be layered,the residence time will increase with the decrease of the first,the particles pulse frequency will decrease with turbulent enhancement,the risk of particle collision and energy dissipation will increase,and it will appear a porosity peak;with the increase of viscosity of fluid phase,the freedom of particles movement will be constrained,the collision contact force will increase,but the pulsation frequency will decrease;With the decrease of the fluid phase velocity,with the decrease of the fluid phase velocity,the residence time will increase more,particles easily settling stranded at the bottom of the micro cracks under the action of gravity because of the process of long time of migration,the particle collision strength and turbulent momentum will decrease.