FEM EquationHeat

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FEM EquationHeat.svg FEM EquationHeat

Menu location
Solve → Heat equation
Default shortcut
Introduced in version
See also
FEM tutorial


This equation describes the heat transfer in rigid and fluid bodies.

For info about the math of the equation, see the Elmer models manual, section Heat Equation.


  1. After adding an Elmer solver as described here, select it in the tree view.
  2. Now either use the toolbar button FEM EquationHeat.svg or the menu Solve → Heat equation.
  3. Change the equation's solver settings or the general solver settings if necessary.

Solver Settings

For the general solver settings, see the Elmer solver settings.

The heat equation provides these special settings:

  • DataBubbles: There is also a residual-free-bubbles formulation of the stabilized finite-element method. It is more accurate and does not include any ad hoc terms. However, it may be computationally more expensive. If both DataBubbles and Data Stabilize are false, no stabilization is used and then the results might easily be nonsensical.


  • DataConvection: The type of convection to be used in the heat equation.
  • DataPhase Change Model: The model use for phase changes (ice to water etc.). The model Spatial 1 is the apparent-heat-capacity method, Spatial 2 and Temporal are effective-heat-capacity methods.
    For more info about the models, see this paper (section (is in German). In the paper it was also shown that Spatial 1 has numerical problems on larger temperature gradients and that Spatial 2 was preferred for the phase change ice to water.

Constraint Information

The elasticity equation takes the following constraints into account if they are set:


For the temperature constraints it is important that they act on a face. Constraints set to lines or vertices are not recognized by the Elmer solver.


The result is the temperature in Kelvin.