GuiCommand:Container| {{GuiCommand Name: FEM ConstraintHeatflux MenuLocation: Model , Thermal boundary conditions and loads , Heat flux load Workbenches: FEM_Workbench SeeAlso: FEM_tutorial }} {{GuiCommandFemInfo Solvers: CalculiX, Elmer }}

FEM ConstraintHeatflux

Description

By default, defines a convective heat flux load on a surface at a temperature $T$ with a film coefficient $h$ and with the environment (sink/ambient) temperature $T{0}$. The convective heat flux $q$ will satisfy: $q=h(T-T{0})$. Optionally, can also define a regular surface heat flux load.

(v1.0)

: Can be also used to define a radiation heat flux on a surface. It satisfies: $q=\epsilon \sigma(T^{4}-T_{0}^{4})$ where $\epsilon$ is the surface emissivity and $\sigma$ is the Stefan-Boltzmann constant.

Usage

1. There are several ways to invoke the command:

   • Press the Heat flux load button.
   • Select the Model → Thermal boundary conditions and loads → Heat flux load option from the menu.

2. Click the Add button. In the 3D view select the face(s) on which the heat flux load should be applied. Optionally, click the Remove button to remove the selected faces from the selection list.

3. Choose the heat flux type and specify its parameters:

   • Surface Convection (default) - convective heat flux, enter the desired Film coefficient and Ambient temperature

   • (v1.0)

     : Surface Radiation - radiation heat flux, enter the surface Emissivity and Ambient temperature

   • Surface heat flux - general heat flux, enter the Surface heat flux in Watts per surface area (W/m\^2)

Notes

• The heat flux load uses the following CalculiX cards depending on the selected mode:

  • *FILM for Surface Convection

  • (v1.0)

    : *RADIATE for Surface Radiation

  • *DFLUX for Surface heat flux

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This page is retrieved from https://github.com/FreeCAD/FreeCAD-documentation/blob/main/wiki/FEM_ConstraintHeatflux.md