Seepage Simulation Of Porous Media Pore Structure Based On Lattice Boltzzmann Method

The pore fracture structure of porous media is widely existing in natural materials and artificial synthetic materials such as coal and rock body structure and molecular materials.The flow of fluid in porous media is called seepage.The traditional seepage research generally starts from a macroscopic point of view and does not concern the actual pores.The specific flow conditions within and within the fracture,therefore,analogous to the pore fracture structure of real porous media and based on the definition of pore fractures,a four-parameter stochastic generation method is used to construct a pore fracture structural model,and a mesoscopic simulation method lattice Boltzmann method is used for porous fractured pore structure Percolation simulation was carried out and the research on the " simulation of pore fracture structure in porous media based on lattice Boltzmann method”was studied.Based on the basic principle of the lattice Boltzmann method,the fluid is driven to flow in the pore fracture structure of the porous medium under pressure difference.The two-dimensional Poiseuille flow theory is used to verify the accuracy of the lattice Boltzmann flow simulation program.The average total error of multiple sets of simulations is 3.0815%.The error is small when the pressure gradient is small and the fluid is laminar.Smaller than 1%,with high accuracy,on the one hand to prove the accuracy of the program,on the other hand,to provide a reference basis for the setting of the flow simulation pressure gradient in this paper.Using the basic principle of four-parameter random generation method,72 groups of pore structure models and 54 groups of fracture structure models were constructed.The pore fracture structure model was selected at random and the accuracy of the four-parameter program was verified by ImageJ software.The total average error of the pore structure model was 0.4707%.The total average error of fracture structure model is 0.5973%.The simulation results show that:(1)There is a good first-order linear relationship between the average pore diameter d and the circularity of the pore R0.The shape,such as R0=-Ad+B,gradually increases with the increase of porosity.The circularity deceleration accelerates;(2)The permeability Kk and the pore average equivalent diameter d approach a quadratic power exponential relation.The permeability has a linear relationship with the porosity Ek,and the inductive fitting relation is:Kk=Ad2Ek-B is basically consistent with the previous empirical formula;(3)The exponential power relation between the permeability KL and the average gap width b,the fitting relational formula such as KL=Ab2,and the bounded square theorem Darcy's law The derivation K=b2/12 is basically the same.As the crack rate increases,the coefficient A shows an increasing trend,that is,the overall increase rate of the permeability becomes larger;(4)Fitting data shows that there is a relationship between the fractal box dimension and the void fissure rate.A better logarithmic relationship,the basic form is D=ALn(E)+B,where the constant B approaches 2.