coupled or connected to the fluid-flow in some way. Process or component cooling are classic examples. The interface includes added functionality for calculating the added dispersion of heat transfer due to turbulence. This is represented by one of the Kays-Crawford or Extended Kays-Crawford Turbulence heat transport models, of by including your own turbulent Prandtl number.

There are four Conjugate Heat Transfer, Turbulent Flow interfaces, and each use the Reynolds-Averaged Navier-Stokes (RANS) equations, solving for the mean velocity field and pressure, along with the k-e model. See Table 13-1 and The Non-Isothermal Flow and Conjugate Heat Transfer, Turbulent Flow Interfaces for details.

Coupling to Other Physics Interfaces

Often, you may be simulating applications that couple heat transfer in turbulent flow to another type of phenomenon described in another physics interface. This can include chemical reactions and mass transport, as covered by the physics interfaces in the Chemical Species Transport branch.

Furthermore, the Chemical Reaction Engineering Module includes, not only support for setting up and simulating chemical reactions, but also for simulating reaction kinetics through the temperature-dependent Arrhenius Expression and Mass Action Law. This interface also includes support for including and calculating thermodynamic data as temperature-dependent expressions, for both reaction kinetics as well as fluid-flow.

In addition, the Heat Transfer Module also includes more detailed descriptions and tools for simulating energy transport, such as surface-to-surface and participating media radiation.

Location of Other Heat Transfer Documentation

Heat transfer through conduction and convection (both non-isothermal flow and conjugate heat transfer) in solid and free media is supported by physics interfaces shipped with the basic COMSOL Multiphysics license. The Joule Heating Interface is described in the COMSOL Multiphysics User’s Guide.

If you are using the Heat Transfer Module with enhanced fluid-flow interface features, due to the presence of the CFD Module, see also the Heat Transfer Module documentation for additional information.

To locate and search all the documentation, in COMSOL, select Help>Documentation from the main menu and either enter a search term or look under Heat Transfer Module in the documentation tree.

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T h e H e a t T r a n s f e r I n t e r f a c e s

The following sections list all the physics interfaces and the features associated with them under the Heat Transfer branch. The descriptions follow a structured order as defined by the order in the branch. Because many of the interfaces are integrated with each other, some features described also cross reference to other interfaces. At the end of this section is a summary of the theory that goes towards deriving the physics interfaces under the Heat Transfer branch.

The Heat Transfer interfaces model heat transfer by conduction and convection. Surface-to-ambient radiation effects around edges and boundaries can also be included. The interfaces are suitable for modeling heat transfer in solids and fluids and in porous media. The interfaces are available in 1D, 2D, and 3D and for axisymmetric models with cylindrical coordinates in 1D and 2D. The default dependent variable is the temperature, T.

These key topics in this section:

•Accessing the Heat Transfer Interfaces via the Model Wizard

•Heat Transfer in Solids

•Heat Transfer in Fluids

•Boundary Conditions for the Heat Transfer Interfaces

Accessing the Heat Transfer Interfaces via the Model Wizard

There are Heat Transfer interfaces displayed in the Model Builder with the same name but with different icons and default models. After selecting a Heat Transfer interface in the Model Wizard, default settings are added under the main node. For example, if

Heat Transfer in Solids () is selected, a Heat Transfer node is added with a default Heat Transfer in Solids model. If Heat Transfer in Fluids () is selected, a Heat Transfer

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in Fluids model is added instead, but the parent nodes are both called Heat Transfer. Any interface based on the main Heat Transfer feature has the suffix ht. Select:

•Heat Transfer in Solids (ht) () to model mainly heat transfer in solid materials. A default Heat Transfer in Solids model is added, but all functionality for including fluid

domains is also available.

•Heat Transfer in Fluids (ht) () to model mainly heat transfer in fluid materials. A default Heat Transfer in Fluids model is added, but all functionality for including solid

domains is also available.

•Heat Transfer in Porous Media (ht) () to model mainly heat transfer in porous materials. The Porous Matrix and Heat Transfer in Fluids models are added, but all

functionality for including solid domains is also available.

Select another interface as required. Select:

•Joule Heating (jh) (), found under the Electromagnetic Heating subbranch (), to combine all features from the Electric Currents interface with the Heat Transfer

interface for modeling Joule heating (also called resistive heating or ohmic heating). See The Joule Heating Interface in the COMSOL Multiphysics User’s Guide.

•Conjugate Heat Transfer (), Laminar Flow (nitf) (), and Turbulent Flow (nitf)

() to use a predefined multiphysics coupling consisting of a Single-Phase Flow interface, using a compressible formulation, in combination with a Heat Transfer

interface. See Non-Isothermal Flow Branch.

The Non-Isothermal Flow (), Laminar Flow (nitf) (), and Turbulent Flow (nitf) () interfaces found under the Fluid Flow branch are identical to the Conjugate Heat Transfer interfaces. The only difference is that Fluid is selected as the default model. If Heat transfer in

solids is selected as the default model, the interface changes to a

Note

Conjugate Heat Transfer interface. To change the default model, select the Heat Transfer interface node and locate the Physical Model section in the Settings window.

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T h e H e a t T r a n s f e r I n t e r f a c e

The Heat Transfer (ht) interface is available in many forms (see Accessing the Heat Transfer Interfaces via the Model Wizard) and each one has the equations, boundary conditions, and sources for modeling conductive and convective heat transfer, and solving for the temperature.

When this interface is added, default nodes are added to the Model Builder based on the selection made in the Model Wizard—Heat Transfer in Solids or Heat Transfer in Fluids,

Thermal Insulation (the default boundary condition), and Initial Values.

Depending on the version of the Heat Transfer interface selected, these

default nodes may be different.

Note

Right-click the Heat Transfer node to add other features that implement, for example, boundary conditions and sources.

I N T E R F A C E I D E N T I F I E R

The interface identifier is a text string that can be used to reference the respective physics interface if appropriate. Such situations could occur when coupling this interface to another physics interface, or when trying to identify and use variables defined by this physics interface, which is used to reach the fields and variables in expressions, for example. It can be changed to any unique string in the Identifier field.

The default identifier (for the first interface in the model) is ht.

D O M A I N S E L E C T I O N

The default setting is to include All domains in the model to define heat transfer and a temperature field. To choose specific domains, select Manual from the Selection list.

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