O v e r v i e w o f t h e U s e r ’ s G u i d e

The CFD Module User’s Guide gets you started with modeling CFD systems using COMSOL Multiphysics. The information in this guide is specific to the CFD Module. Instructions how to use COMSOL in general are included with the COMSOL Multiphysics User’s Guide.

As detailed in the section Where Do I Access the Documentation and Model Library? this information is also searchable from the COMSOL

Tip Multiphysics software Help menu.

T A B L E O F C O N T E N T S , G L O S S A R Y , A N D I N D E X

To help you navigate through this guide, see the Contents, Glossary, and Index.

Q U I C K S T A R T G U I D E

The Quick Start Guide includes some basic modeling strategies to help you begin modeling fluid flow for your particular application area. For example, it gives some tips about how to control your material properties and set the optimal mesh to make solving the model easier and quicker. It also includes a summary of all the physics interfaces included with the CFD Module.

T H E C H E M I C A L S P E C I E S T R A N S P O R T B R A N C H I N T E R F A C E S

The Chemical Species Transport Branch include the Transport of Diluted Species and Transport of Concentrated Species interfaces, which are used for the simulation of chemical reactions, and mass or material transport through diffusion, convection and electromigration. The Mechanisms for Chemical Species Transport helps you select the best interface to use. The rest of the section describes the interfaces in detail as well as the underlying theory.

T H E F L U I D F L O W B R A N C H I N T E R F A C E S

There are several fluid-flow physics interfaces available. The various types of momentum transport that you can simulate includes laminar and turbulent flow, Newtonian and non-Newtonian flow, isothermal and non-isothermal flow, multiphase flow, and flow in porous media. Such flow can occur in thin-films or in bounded regions, and in stationary and rotating environments. Every section describes the

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applicable interfaces in detail and concludes with the underlying theory for the interfaces.

Single-Phase Flow

Single-Phase Flow Branch chapter describes the many interfaces available for laminar and turbulent flow. The Mechanisms for Modeling Single-Phase Flow Interfaces helps you choose between the different interfaces that have subtle differences between them.

Thin-Film Flow

Thin-Film Flow Branch chapter describes the Lubrication Shell and Thin-Film Flow interfaces. If you also have the MEMS Module, the Film-Damping Shell and Thin-Film Gas Flow interfaces are also available. The Mechanisms for Modeling Thin-Film Flow Interfaces helps you select the correct interface to use.

Multiphase Flow

Multiphase FlowBranch chapter describes the Laminar Two-Phase Flow, Level Set and Phase Field interfaces, the Turbulent Two-Phase Flow, Level Set and Phase Field interfaces, the Laminar Bubbly and Laminar Turbulent Flow interfaces, and the Laminar and Turbulent Flow Mixture Model interfaces. Some multiphase flow is described using the Phase Field and Level Set interfaces found under the Mathematics>Moving Interface branch. In the CFD Module these features are integrated into the relevant physics interfaces. To help you select which interface to use see The Mechanisms for Modeling Multiphase Flow.

Euler-Euler Model

The Euler-Euler Model Branch chapter describes the Euler-Euler Model, Laminar Flow interface, which has the equations, boundary conditions, and volume forces for modeling flow of two continuous and fully interpenetrating phases.

Porous Media and Subsurface Flow

Porous Media and Subsurface Flow Branch chapter describes the Darcy’s Law, Brinkman Equations, and Free and Porous Media Flow interfaces. To help you select which interface to use see The Mechanisms for Modeling Porous Media and Subsurface Flow.

High Mach Flow

High Mach Number Flow Branch chapter describes three variations of the same predefined multiphysics interface that combine the heat equation with either a laminar or a turbulent flow. The advantage of using the multiphysics interfaces—compared to adding the individual interfaces separately—is that you find predefined couplings in both directions.

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Non-Isothermal Flow

Non-Isothermal Flow Branch chapter describes both the Non-Isothermal Flow and Conjugate Heat Transfer Laminar and Turbulent Flow interfaces. To help you select which interface to use see The Mechanisms for Modeling Non-Isothermal Flow.

H E A T T R A N S F E R B R A N C H I N T E R F A C E S

The module includes interfaces for the simulation of heat transfer. As with all other physical descriptions simulated by COMSOL Multiphysics, any description of heat transfer can be directly coupled to any other physical process. This is particularly relevant for systems based on fluid-flow, as well as mass transfer. The interfaces also allows you to account for heat sources and sinks, such as energy evolving from chemical reactions. Heat Transfer Branch chapter describes the enhanced Heat Transfer interfaces, including the Out-of-Plane Heat Transfer features. It also describes the Heat Transfer in Porous Media interface. To help you select which interface to use see The Mechanisms for Modeling Heat Transfer in the CFD Module. The rest of the chapter describes these interfaces in detail as well as the underlying theory.

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Q u i c k S t a r t G u i d e

This chapter has some basic modeling strategies to help you get started modeling fluid flow in your application area.

In this chapter:

•Modeling and Simulations of Fluid Flow

•The CFD Module Physics Interfaces

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