A greyscale volumetric lattice Boltzmann method for upscaling pore-scale two-phase flow
A greyscale volumetric lattice Boltzmann method for upscaling pore-scale two-phase flow
复制标题
DOI：
10.1016/j.advwatres.2020.103711
复制
发表时间：
2020-10-01
影响因子：
4.7
通讯作者：
Niasar, Vahid
中科院分区：
文献类型：
--
作者：
An, Senyou;Zhan, Yuting;Niasar, Vahid
基于图像的多孔介质孔隙尺度流动和输运问题的求解是水文地质、油藏工程、造纸和过滤工程等领域基础研究和工业研究的主流。这一研究学科需要图像处理，计算流体建模和高性能计算的多学科研究领域的巨大整合。孔隙尺度多相流模拟的关键挑战是压倒性的计算费用。在本文中，我们开发了一种新的计算方法，集成了GPU加速的体积格子玻尔兹曼方法（VLBM）与升尺度方案，以解决在厘米级的长度尺度的孔隙尺度的两相流。格子玻尔兹曼的概念来解决图像分割的水平集方程和多相流动力学的控制方程。从水平集方程求解的符号距离场用于计算每个晶格单元的空隙体积比，从而实现图像分割和计算流体动力学之间的无缝连接。孔尺度多孔材料的放大是通过相邻单元的平均空隙体积比来进行的。该算法在三种情况下进行了严格的测试：两个板之间的液滴的接触角测试，并流在圆柱管中，和砂岩样品中的两相流。对于砂岩样品，孔隙度，孔隙空间拓扑结构，相对渗透率和优先流动通道在8倍放大后得到很好的保留，而计算时间显着减少。
Solving image-based pore-scale flow and transport in porous materials is a mainstream of fundamental and industrial research to reveal the pertinent physics in the field of hydrogeology, reservoir engineering, paper and filter engineering. This research discipline requires tremendous integration of multidisciplinary research areas of image processing, computational fluid modelling, and high-performance computing. The key challenge in porescale multi-phase flow simulation is the overwhelming computational expense. In this paper, we develop a new computational method that integrates GPU-accelerated volumetric lattice Boltzmann method (VLBM) with an upscaling scheme to solve the pore-scale two-phase flow at the centimetre-level length scales. The lattice Boltzmann concept is employed to solve both the level-set equation for image segmentation and governing equations for multi-phase flow dynamics. The signed distance field solved from the level set equation is used to calculate the void volume ratio of each lattice cell, resulting in a seamless connection between image segmentation and computational fluid dynamics. The pore-scale porous materials upscaling is carried out through the average void volume ratio of the neighbouring cells. The algorithm is rigorously tested in three cases: contact angle test for droplets between two plates, co-current flow in a cylindrical tube, and the two-phase flow in a sandstone sample. For the sandstone sample, the porosity, void space topology, relative permeability and preferential flow channels are well retained after 8-times upscaling, while the computational time is dramatically decreased.