Overview of the User’s Guide
The Subsurface 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 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 Flow Branch
The single-phase flow interfaces Laminar Flow and Creeping Flow are described in Chapter Single- and Multiphase Flow Interfaces.
The Multiphase Flow Branch
The Phase Transport Interfaces section describes the transport of multiple immiscible phases in free and porous media flow.
The Porous Media Flow Branch
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.
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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.
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The Darcy’s Law Interface is for flow in porous media that is relatively slow.
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The Two-Phase Darcy’s Law Interface to simulate two-phase slow flow through interstices in a porous medium.
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The Richards’ Equation Interface is for variably saturated systems.
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The Fracture Flow Interface is a special application of Darcy’s law for modeling flow in fractures.
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The Brinkman Equations Interface is for fast flow in porous media flow.
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The Free and Porous Media Flow, Brinkman Interface and The Free and Porous Media Flow, Darcy Interface are for modeling fluid flow in systems with both free and porous media flow.
The Shallow Water Equations Branch
The Shallow Water Equations Interface chapter describes The Shallow Water Equations, Time Explicit Interface and includes the underlying theory. It is suitable in cases where the horizontal length scale is much greater than the vertical length scale.
The Chemical Species Transport Branch
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 Heat Transfer Branch
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.
When you have the Subsurface Flow Module plus the Chemical Reaction Engineering and/or Heat Transfer Modules, 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 chapter 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 Multiphase Flow in Porous Media Interface combines the functionality of the Darcy’s Law and Phase Transport in Porous Media interfaces.
The Reacting Flow in Porous Media Interface combines the Brinkman Equations and the Transport of Diluted Species in Porous Media interfaces.
The Nonisothermal Flow, Brinkman Equations Interface couples porous media flow and heat transfer by combining the Brinkman Equations and the Heat Transfer in Porous Media interfaces.