Overview of the User’s Guide
The Porous Media Flow Module User’s Guide gets you started with modeling using COMSOL Multiphysics. The information in this guide is specific to this module. Instructions how to use COMSOL Multiphysics in general are included with the COMSOL Multiphysics Reference Manual.
As detailed in the section Where Do I Access the Documentation and Application Libraries? this information can also be searched from the COMSOL Multiphysics software Help menu.
The Single-Phase and the Multiphase Flow Branch
The Single- and Multiphase Flow Interfaces section describes the Laminar and Creeping Flow interfaces. The Phase Transport Interfaces are used to model the transport of multiple immiscible phases in free and porous media flow. They are described in the CFD Module User’s Guide and just referenced here.
The Porous Media Flow Branch
The Porous Media and Subsurface Flow Interfaces chapter describes the following physics interfaces and includes the underlying theory for each physics interface at the end of the chapter.
•
The Porous Media and Subsurface Flow group of interfaces estimates the pressure and velocity of fluids flowing in free systems and within the interstices of a porous medium. Theory for the Darcy’s Law Interface helps you choose the right physics interface to use.
•
The Darcy’s Law Interface is intended for flow in porous media that is relatively slow.
•
The Richards’ Equation Interface is intended for variably saturated systems.
•
The Fracture Flow Interface is a special application of Darcy’s law for modeling flow in fractures.
•
The Layered Darcy’s Law Interface is intended for flow in porous media that is relatively slow.
•
The Brinkman Equations Interface is intended for fast flow in porous media flow.
•
The Free and Porous Media Flow, Brinkman Interface and The Free and Porous Media Flow, Darcy Interface are intended for modeling fluid flow in systems with both free and porous media flow.
The Chemical Species Transport Branch
The Chemical Species Transport Interfaces chapter describes the physics interfaces found under the Chemical Species Transport branch when adding a physics interface. The Transport of Diluted Species interface is used to compute the concentration field of a dilute solute in a solvent. Transport and reactions of the species dissolved in a gas, liquid, or solid can be computed.
The Transport of Diluted Species in Porous Media Interface characterizes the fate and transport of individual or multiple and interacting chemical species for systems containing fluids, solids, and gases. Theory for the physics interfaces is included at the end of the chapter.
The Transport of Diluted Species in Fractures Interface is used to model the transport of a solute species along thin fractures. The interface takes into account diffusion, dispersion, convection, and chemical reactions in fractures. The fractures are defined by boundaries in 2D and 3D, and the solute species is assumed to be diluted in a solvent. The mass transport equation solved along the fractures is the tangential differential form of the convection–diffusion–reaction equation.
The Moisture Transport Interfaces are five different interfaces that can be used to model moisture transport in porous media and building materials as well as moist air. The different transport mechanisms are taken into account as well as if the liquid and gas phase are in equilibrium or not.
The Moisture Transport in Solids Interface is used to model moisture diffusion in a solid.
The Heat Transfer Branch
The Heat Transfer Interfaces chapter describe the group of interfaces that estimate the temperature distribution in solids, fluids, and fluid-solid systems. The Mechanisms for Heat Transfer helps you choose the physics interface to use. It includes physics interfaces to estimate effective properties in multicomponent systems. All heat transfer interfaces come with interfaces to account for a geotherm brought about through radiogenic decay.
The Heat Transfer Interface models heat transfer by conduction and convection. Surface-to-ambient radiation effects around edges and boundaries can also be included. The physics interfaces are available in 1D, 2D, and 3D and for axisymmetric models with cylindrical coordinates in 1D and 2D.
The Heat Transfer in Porous Media Interface lets you describe heat transferred both with and without flowing fluids. You can define the velocity in the convective term with any of the flow equations just mentioned or set it with an arbitrary expression. With convective heat transfer, the effective thermal properties also include an option to estimate the dispersion or spreading of heat from small-scale velocity variations
The Local Thermal Nonequilibrium Interface solves two heat transfer equations in the solid and fluid phases, to model heat transfer in porous media for which the solid and fluid temperatures are not in equilibrium.
When your license includes the Porous Media Flow Module plus the Chemical Reaction Engineering Module or Heat Transfer Module, the Heat Transfer interface also has extended features available.
The Multiphysics Coupling Nodes
In the Multiphysics Interfaces and Couplings chapter the predefined multiphysics interfaces are introduced.
The Poroelasticity, Solid Interface section describes the physics interface for Biot’s poroelasticity, and combines Darcy’s law with solid mechanics to provide suitable settings to describe the interaction between porous media and fluids.
The Unsaturated Poroelasticity Interface combines a transient formulation of Moisture Transport in Solids with a quasistatic formulation of Solid Mechanics. The pore pressure from the Moisture Transport in Solids interface acts as a load for the Solid Mechanics interface, causing swelling or shrinking.
The Multiphase Flow in Porous Media Interface combines the functionality of the Darcy’s Law and Phase Transport in Porous Media interfaces.
The Moisture Flow Interface couples moisture transport in air by vapor diffusion and convection with a laminar flow interface.
The Heat and Moisture Transport Interfaces couple heat transfer and moisture transport in building materials or in moist air, respectively.
The Heat and Moisture Flow Interface combines the functionalities of three different interfaces: Laminar flow, Moisture Transport in Air, and Heat Transfer in Moist Air.
The Reacting Flow in Porous Media Interface combines the Brinkman equations with the Transport of Diluted Species interface.