## 1. Introduction

All elements for heat transfer analysis are isoparametric. The degrees-of-freedom are the temperatures at the element nodes. The gradients are the heat fluxes in x-, y-, and (for the three-dimensional elements) z-direction.

## 2. Element Types

For heat conduction, the following continuum element types are available:

Table 19. Two-dimensional Heat Conduction Elements

 T3.HEAT.CONDUCTION T6.HEAT.CONDUCTION Q4.HEAT.CONDUCTION Q8.HEAT.CONDUCTION Q9.HEAT.CONDUCTION

Table 20. Three-dimensional Heat Conduction Elements

 TE4.HEAT.CONDUCTION TE10.HEAT.CONDUCTION PR6.HEAT.CONDUCTION PR15.HEAT.CONDUCTION HE8.HEAT.CONDUCTION HE20.HEAT.CONDUCTION HE27.HEAT.CONDUCTION

The one-dimensional line elements and the two-dimensional surface elements for specifying convection and radiation conditions (von-Neumann conditions) are 'overlay' elements, i.e. they are added to edges or faces of heat conduction element. The element geometry is explained in the Element Naming and Numbering Conventions. These elements do not have own degrees of freedom. The following element types are available:

Table 21. One-dimensional Heat Convection and Heat Radiation Elements

Table 22. 3D Heat Convection and Heat Radiation Elements

## 3. Required MDL Element Attributes

mid m

Specifies the element material number m. The referenced material must be of type heat.

## 4. Optional MDL Element Attributes

group eid

Defines the element group number gid (a non-negative integer number). The default group number is 0. The same definition will be used for all elements defined hereafter, until a new group option is encountered or until the eltype command is specified.

mbase flag e11 e12 e13 e21 e22 e23 e31 e32 e33

Specifies the material reference coordinate system base. The lists starts with a flag and the components of the three base vectors.

flag denotes the reference system in which the material base is defined. A value of 0 indicates that the material reference coordinate system is identical to the branch coordinate system. The following base vectors are then dummy vectors. A value of 1 indicates that the material reference coordinate system is defined by base vectors with respect to the branch coordinate system. A value of 2 indicates that the material reference coordinate system is defined by base vectors with respect to the element-local coordinate system. A value of 3 indicates that the material reference coordinate system is defined by base vectors with respect to the integration point local coordinate system. A value of 11 indicates that the material reference coordinate system is defined by angles of orientation with respect to the branch coordinate system. A value of 12 indicates that the material reference coordinate system is defined by angles of orientation with respect to the element-local coordinate system. A value of 13 indicates that the material reference coordinate system is defined by angles of orientation with respect to the integration point local coordinate system. Note that the default element material reference coordinate system is element-dependent, see Element Naming and Numbering Conventions.