Heat transfer

The material properties for heat transfer problems are defined by two quantities:

the thermal conductivity $\lambda~[\text{W}/\text{mK}]$,
the volumetric heat capacity $\rho c~[\text{J}/\text{m}^3\text{K}]$.

In the name.iB file, all materials used are first defined using MP sets:

MP set number T 1 V $\lambda$ $\rho c$

Material properties must be assigned in the first load case and apply to all load cases. First, one of the defined sets (the default set) is assigned to the entire body:

AS 1 /M set number /$\dots$

If some elements have material properties different from those described by the default set, additional sets are assigned to them:

AS 1 /M set number$_1$ /M set number$_2$ E element number list$_2$ /M set number$_3$ E element number list$_3$/$\dots$

Note
More than one assignment of material properties to a single element may occur within an AS batch. In that case, the material properties are overwritten. Only the last assigned set therefore applies.

Note
In heat transfer problems, material properties can depend on the global coordinates $x$, $y$, $z$ and the temperature $T$, using any of the available functional dependencies, see the Reference Manual.

Example

Let us consider two materials with constant properties $\lambda_1=2~\text{W}/\text{mK}$, $\lambda_2=20~\text{W}/\text{mK}$, and $\rho_1c_1=\rho_2c_2=3\cdot10^6~\text{J}/\text{m}^3\text{K}$. The thermal conductivity $\lambda_2$ applies to the entire body, $\lambda_1$ to elements 11 through 25.

The name.iB file will contain:

⋮
MP 1 T 1 V 2 3.0e6
MP 2 T 1 V 20 3.0e6
⋮
AS 1 /M 2 /M 1 E 11:25
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Example

Let us consider a material with constant thermal conductivity $\lambda_1=20~\text{W}/\text{mK}$ and with a volumetric heat capacity that depends on temperature:

$T~[^\circ\text{C}]$	$400$	$600$	$800$
$\rho c~[\text{J}/\text{m}^3\text{K}]$	$4.10\cdot10^6$	$4.3\cdot10^6$	$4.6\cdot10^6$

The dependence is described using a table (see the Reference Manual), where the temperature has identification number 5 (see the Reference Manual).

The name.iB file will contain:

⋮
IV 1 T 5 V 400 600 800
⋮
MP 1 T 1 I 1 V 3*20 V 4.1e6 4.3e6 4.6e6
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