FEM ConstraintBodyHeatSource

Description
Defines a internally generated body heat given in W/kg (not J/m³). Please see https://forum.freecadweb.org/viewtopic.php?f=18&t=44705&start=490#p422539 and following and also Elmer "Tutorial 1 - Heat equation – Temperature field of a solid object" in https://www.nic.funet.fi/pub/sci/physics/elmer/doc/ElmerTutorials.pdf for more detailed information.

Usage

 * 1) There are several ways to invoke the command:
 * 2) * Press the button.
 * 3) * Select the option from the menu.
 * 4) In the 3D view select the objects the constraint should be applied to, which can be a vertices (corners), edges, or faces.
 * 5) Enter a specific heat value to apply to the objects.