MRT-LB Numerical Simulation Of And Displacement Process In Porous Media

Fluid flow in porous media has a wide range of applications,such as the flow in porous media with internal heat sources commonly found in nuclear reactor safety design,item drying,nuclear waste disposal,cooling of electronic devices,exothermic chemical reactions in particle accumulation beds,etc.The displacement process in porous media such as petroleum exploitation in the surface layer,CO2 storage in geological stratification,composite material molding,etc.Lattice Boltzmann method(LBM)is a numerical simulation method based on mesoscale model.It has developed rapidly in recent years and has played an indispensable role in fluid modeling and numerical simulation research.This method has different from the traditional numerical simulation method,it is based on the mesoscopic kinematics theory,and it's physical background is clear.It has natural parallel characteristics,and the algorithm is simple and easy to implement.In this paper,the multiple relaxation time lattice Boltzmann(Multiple-Relaxation-Time Lattice Boltzmann,MRT-LB)method is used to numerically solve the problem of natural convection heat transfer in the porous cavity with a heat source placed on the bottom and two-phase displacement flow process in porous media.The main conclusions are as follows:First,this paper uses single-phase MRT-LBM to simulate the natural convection phenomenon with single heat source or double heat source in the square cavity of porous medium.In the case of single heat source,the effects of the width,height,and lateral displacement of the bottom heat source on the flow and heat transfer in the cavity are discussed.In the case of dual heat sources,the effect of the bottom heat source's spacing on the flow heat transfer is discussed.The results show that with the increase of the width of the heat source,the heat transfer intensity of the upper wall of the heat source increases,the heat transfer intensity of the left and right walls don't change significantly.The increase in the height of the heat source will weaken the heat transfer effect on the upper wall of the heat source,but the heat transfer intensity of the left and right walls will be greatly improved,and the overall heat transfer will be enhanced.The increase of the lateral displacement of the heat source at the bottom of the square cavity causes the heat transfer efficiency of the left wall surface of the heat source to gradually decrease,and the upper wall surface will reach a minimum value before increasing,but the process has no significant impact on the heat transfer efficiency of the right wall surface.In the case of dual heat sources,the low temperature area in the square cavity is significantly reduced,and the increase in the distance between the heat sources will increase the heat exchange efficiency of the adjacent side wall surface and the upper wall surface of the heat source,and the overall heat exchange efficiency will be improved.Secondly,the modified multi-phase and multi-component Shan-Chen pseudo-potential MRT-LB method is used to simulate the gas-liquid two-phase displacement process in porous media.The Re number of inlet boundary,type structure,and porosity of porous media,the contact angle with the wall are analyzed and discussed on the displacement process.The results show that in the same porous medium structure,with the increase of the inlet Re number,the difference between the gas-liquid interface at different positions in the channel is also greater,the smaller the gas saturation in the channel at the end of the displacement process,the liquid remains the less.Secondly,in porous media with different structures and the same porosity,at the end of the displacement process,the media has same gas saturation,but the displacement process needs different time,the longitudinal ellipse structure requires the shortest time,and the circular structure's time required is second,and the horizontal ellipse structure takes the longest time.The larger the fractal order has the smaller the porosity and the shorter time required for displacement.However,the difference in the coordinates of the gas-liquid interface at different locations increases with the decrease in porosity,and the gas is saturated when the displacement is completed.The greater the wall contact angle,the smaller the gas saturation,the more liquid remains in the channel,and the lower the liquid recovery rate.