Experiments Study And Numerical Simulation Of Particle Migration And Deposition At The Fluid/Porous Media Interface

Migration and deposition of micro particles widely occurs in natural and many industrial processes when fluid flows through porous media,which involves hydrogeology,fluid mechanics,physical chemistry,heat transfer and many other fields.In this paper,physical clogging of micro particles during geothermal reinjection into sandstone was taken as the research background,the migration and deposition of micro particles at the fluid/porous media interfaces was studied through experiments and numerical simulation.Previous studies have been focused on the particle migration inside the porous media,and few studies was about the deposition characteristics of micro-particles at the interface of porous media,the effect of temperature gradients at the interface on particle deposition has not yet been studied.In this paper,an experimental system for the particle deposition at the fluid/porous media interfaces under static conditions was set up,the positive/negative temperature gradients at the interface were achieved by thermostatic water bath,and the effect of the temperature gradient was studied.The results show that:(1)The amount of particle deposition increases as temperature gradient increases,however,when the positive temperature gradient is small,the deposition amount of particles increases little or even decreases.This is because the temperature gradient results in a natural convection in the experimental section,causing changed in particle deposition.(2)The deposition rate of particles decreases exponentially as the amount of particle deposition increases,and based on the experiment data,a mathematical model of the particle deposition with time and temperature gradient is obtained,by modifying the kinetic equation of particle deposition.This paper numerically simulated the effects of the density and concentration of micro particle,and the ratio of particle size and porous media pore size,on the particle migration at the interface of porous media.The Lattice-Boltzmann method,which is easy to deal with complex boundaries,is used to simulate the fluid flow.By Newton's law to deal with the particle movement,can solve the influence of particle size,geometry and deposition morphology on particle interaction,which is difficult to solve for the previous numerical simulation.The conclusions are as follows:(1)With the increase of the particle density,the deposition amount of micro particle both at the interface and inside porous media increases.The greater the particle density,the earlier the particle clogging occurs at the interface.(2)The particle concentration has no significant effect on the deposition amount of micro particle at the interface and the stable deposition rate,but affects the time of clogging at the interface.(3)With the decreases of particle size ratio of micro particle to porous media,at the same time,the total deposition amount of micro particle per unit area of porous media increases.The less the particle size ratio,the less time it taken for particles to fill the porous media.By qualitative comparison between the numerical simulation and experimental data without temperature,it is found that deposition amount of particles changes with time and the deposition visualization are in good agreement.