基于LB方法平板流立方定律的数值模拟研究

Study on Numerical Simulation of Cubic Law of Plate Flow Based on Lattice Boltzmann Method

格子Boltzmann方法模拟岩体裂隙渗流场,较传统的数值模拟具有天生的并行特性、边界条件处理简洁、程序易于实施、能得到清晰的物理图像等独特优势。通过JRC数值生成法建立起在一定范围内的节理粗糙度系数JRC的二维岩体吻合裂隙结构。基于格子Boltzmann方法(LBM),设置出入口为非平衡态外推格式、上下岩体裂隙表面为标准反弹格式的边界条件,建立了模拟岩体裂隙渗流模型。通过C++编程实现格子Boltzmann方法模拟并验证了经典的泊肃叶流动。压力差为0.002和隙宽比为400:21的粗糙裂隙内,岩体裂隙渗流流态是线性次立方水流,并且随节理裂隙粗糙度系数JRC值的增加,次立方值偏离数值3越明显。在JRC=14.1的情况下,裂隙渗流在不同压力差驱动和不同隙宽、不同压力差下,可表现为次立方渗流、立方渗流和超立方渗流。

Lattice Boltzmann Method(LBM)has been used to simulate the seepage field of the fractured rock masss,which is born with the advantages of parallel characteristics,simple boundary conditions,easy to implement the program,clear physical image compared with the traditional numerical simulation.JRC numerical generation method is used to establish the fracture structure of two-dimensional rock mass with JRC of the joint roughness coefficient in a certain range.Based on the Lattice Boltzmann Method(LBM),the the boundary conditions are that the inlet and outlet are set to the non-equilibrium extrapolation scheme,and the crack surface of the upper and lower rock mass is set to the standard rebound format.C++programming can realize the Lattice Boltzmann Method simulation and verify the classic Poiseuille flow.In the rough fracture with a pressure difference of0.002and the width ratio of400:21,the flow pattern of the rock mass seepage is linear sub-cubic flow,and with the increase of the JRC value,the deviation of the cubic value from the value of3is more obvious.In the case of JRC=14.1,the the fracture seepage can be represented by the sub-cubic seepage,cubic seepage and super-cubic seepage under different pressure difference and different fracture width.