Numerical Simulation Of Seepage In Porouse Media Based On Latticee Boltzmann And Upscaling

The seepage of porous media is a complex flow process that is widely involved in multidisciplinary fields such as environment and energy,and it has typical multi-scale characteristics.Numerical simulation of pores can obtain detailed information about fluid flow in porous media.However,the unknown amount of "degree of freedom" for pore simulation is huge,the calculation is extremely time-consuming,and the results are difficult to apply to actual projects.The up scaling process obtains macroscopic equivalent parameters by analyzing the pore flow law,and then realizes relatively fast calculation.Based on this,in view of the physical problems of porous media seepage,this paper carried out numerical simulation of pores based on lattice Boltzmann and scale-up research based on parameter transfer,and realized the combination of "Pore-Darcy-Reduced-order" model of porous media seepage.The up scaling process is as follows:First of all,this paper studies the internal flow laws of different types of porous media such as pores,cracks,and fissures in turn based on lattice Boltzmann.Studies have shown that the porosity of porous media and the structure of its solid framework have an important influence on its internal flow,and the fluid permeability in fractures is significantly greater than the pore permeability.In the test case of this paper,the flow rate of the fractured medium is nearly two orders of magnitude higher than that of the original porous medium;for different types of porous media,within the range of the studied pressure difference,the internal flow meets the law described by Darcy's law.Secondly,the equivalent permeability of the typical porous media structure is obtained through pore simulation,and the process of "Pore-Darcy" upscaling is realized.The calculation result of the test case reflects the macroscopic law of pore flow,which is a coarse expression of pore flow;The schemes of random sampling and sub-area sampling to solve the permeability are compared and studied.The sub-area sampling scheme can reduce the influence of random factors and reduce the deviation caused by upscaling to less than10%.On the basis of the above research,through the POD low-order model and the POD basis function as the medium,the scale of "Pore-Darcy-Reduced-order" has been improved.The calculation example in this paper shows that the maximum relative deviation between the calculation result and the average flow rate simulated by the pore scale is 9.23%,but the scale increase has a significant acceleration effect,and the acceleration ratio reaches 195 times.It has good prospects in pratical applications.