If Crosswind diffusion is selected, enter a Lower gradient limit glim (SI unit: K/m). The default is 0.01[K]/ht.helem.

	• Model Builder Options for Physics Feature Node Settings Windows
	In the COMSOL Multiphysics User’s Guide:
	•	Show Stabilization
See Also	•	Consistent and Inconsistent Stabilization Methods for the Heat
		Transfer Interfaces
	• Theory for the Heat Transfer Interfaces

Heat Transfer in Solids

The Heat Transfer in Solids model uses the heat equation version in Equation 13-1 as the mathematical model for heat transfer in solids:

C	T	– k T = Q	(13-1)
	------
	p t

For a steady-state problem the temperature does not change with time and the first term disappears. It has these material properties: density , heat capacity Cp, thermal conductivity k (a scalar or a tensor if the thermal conductivity is anisotropic), and Q, which is the heat source (or sink)—one or more heat sources can be added separately.

•2D Heat Transfer with Convection: Model Library path

COMSOL_Multiphysics>Heat_Transfer>heat_convection_2d

Model

When parts of the model (for example, a heat source) are moving, right-click the Heat Transfer in Solids node to add a Translational Motion feature to take this into account.

Add Pressure Work to the Heat Transfer in Solids node as required.

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

From the Selection list, choose the domains to define the heat transfer. The default is

to use all domains.

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M O D E L I N P U T S

This section contain fields and values that are inputs to expressions that define material properties. If such user-defined material models are added, the model inputs appear here. Initially, this section is empty.

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

The Global coordinate system is selected by default. The Coordinate system list contains any additional coordinate systems that the model includes (except boundary coordinate systems). The coordinate system is used for interpreting directions of orthotropic and anisotropic thermal conductivity.

H E A T C O N D U C T I O N

The default setting is to use the Thermal conductivity k (SI unit: W/(m·K)) From material. If User defined is selected, choose Isotropic, Diagonal, Symmetric, or Anisotropic based on the characteristics of the thermal conductivity, and enter another value or expression.

The thermal conductivity describes the relationship between the heat flux vector q and the temperature gradient T as in q = k T which is Fourier’s law of heat conduction. Enter this quantity as power per length and temperature.

The components of a thermal conductivity k in the case that it is a tensor (kxx, kyy, and so on) are available as ht.kxx, ht.kyy, and so on (using the default Heat Transfer interface identifier ht). The single scalar mean effective thermal conductivity ht.kmean is the mean value of the diagonal elements kxx, kyy, and kzz.

T H E R M O D Y N A M I C S

The default Density (SI unit: kg/m3) and Heat capacity at constant pressure Cp

(SI unit: J/(kg·K)) use values From material. Select User defined to enter other values or expressions. The heat capacity at constant pressure describes the amount of heat energy required to produce a unit temperature change in a unit mass.

•Axisymmetric Transient Heat Transfer: Model Library path

COMSOL_Multiphysics>Heat_Transfer>heat_transient_axi

Model

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