Microscale simulation of three-fluid flow in porous media

Three-fluid systems arise in contaminated unsaturated and saturated porous media, carbon sequestration in worked out petroleum reservoirs, and enhanced oil recovery processes. Fundamental understanding of these complex systems is lacking at both the microscale and macroscale. In this work, we develop and evaluate a three-dimensional, three-fluid-phase microscale simulator based upon the lattice Boltzmann method. We extend the color model routinely used for two-fluid-phase systems to three fluid phases for a D3Q19 lattice and approximate the collision operator using a multiple relaxation time method. Algorithms and data structures are used to enable efficient simulation on hybrid node high-performance computers consisting of both a GPU and CPU cores on each node. We validate the simulator through a variety of tests including a nested bubble test, contact angle control, spinodal decomposition of fluid distributions, and a compound-drop cylinder problem. Weak scaling performance data shows high efficiency of the developed simulator up to more than 1000 hybrid nodes. Lastly, the three-fluid phase simulator results in several new macroscale quantities of interest, which can be obtained from microscale simulations. These quantities are identified and real time computation of these quantities is implemented in the simulator and shown in example simulations.