Model Study On Liquid-solid Coupling Of Water-air Two Phase Flow In Porous Media

Nowadays many problems are related to water-gas two phase flow ingeotechnical engineering, it’s usually regarded that water-air two-phase flow canarouse the deformation of the solid skeleton, moreover, skeleton deformation wouldaffect the process of water-gas two-phase flow, which is called water-air two phasefluid-solid coupling process. It’s very important to study on fluid-solid coupling ofwater-air two phase in the actual project. Now it’s related to fluid-solid coupling ofwater-air two phase in many fields, such as hydro-engineering project, undergroundengineering, environmental engineering, oil/gas resource exploitation and so on. It’snecessary to model of fluid-solid coupling of water-air two phase for numericalsimulation analysis as soon as quickly. Fluid-solid coupling of water-air two phaseinvolves the rock mechanics, geology, fluid mechanics, and other disciplines, which isa issue of multiple discipline interaction. There are three basic algorithms: a fullcoupling, a loose coupling, and a one way coupling. In the full coupling, a single setof governing equations to handle both mechanics and fluid flow must be derived.However, derivation of the set of governing equations is difficult. The one-waycoupling does not reflect the mutual coupling effects. So in this paper the loosecoupling is used to model fluid-solid coupling of water-air two phase. Therefore it’sneeded to model fluid-solid two phase flow in the unsaturated soil and solid skeletondeformation mechanics, after that, combine with one coupling modeling. In this paper,the loose coupling is used to simulate liquid-solid coupling of water-air Two phaseflow in porous media, TOUGH2, a computer code for multiphase multi componentnon isothermal flow in three-dimensional porous and fractured media, is used tosimulate fluid flow. FLAC3D, an explicit finite differences program for scientificengineering calculations in three dimensions, is used to simulate mechanical system.The main points are as follows:(1)According to the simulation needs, based on the mutual influence betweenrheological process and mechanical process in fluid-solid coupling of water-air twophase, this paper has presented some coupling relationships, such as water saturationand density, pore pressure; porosity and absolute permeability, capillary pressure.(2)It’s based on the FLAC3Dmesh, TOUGH2mesh information is extracted by fishlanguage. After that, some data blocks in the TOUGH2,such as ELEME,CONNE, etc.,which are used to generate TOUGH2mesh, are created by one high-level language. In this way is the generated coupling mesh fully compatible, capable of seamlesslycoupled.(3)The use of C++development FLAC-TOUGH interface program.FLAC-TOUGH interface program can control TOUGH2and FLAC3Dorderly runningand transmit relevant state variables, so we can achieve fluid-solid couplingsimulation of water-air two phase.(4)Pore pressure and density changes can be takeninto account the stress and deformation by a special stress correction way. ForFLAC3Dv4.0previous versions, it’s recommended a traversal node unit bodyalgorithm and a corresponding solutions. So no matter can model be seamlesscoupling towards pore pressure, so that improve the accuracy ofsimulation.(5)FLAC-TOUGH interface program simulate on-site pressure gas test inEssen, German. Simulation results show that the interface program, which is used offluid-solid coupling of water-air two phase, is feasible and valid.