FEM ConstraintHeatflux

Description

Defines a heat flux load on a surface. The following heat flux types are supported:

• regular surface heat flux load ${\displaystyle q}$
• convective heat flux load on a surface at a temperature ${\displaystyle T}$ with a film coefficient ${\displaystyle h}$ and with the environment (sink/ambient) temperature ${\displaystyle T_{0}}$. The convective heat flux ${\displaystyle q}$ will satisfy: ${\displaystyle q=h(T-T_{0})}$.
• introduced in 1.0: radiation heat flux on a surface. It satisfies: ${\displaystyle q=\epsilon \sigma (T^{4}-T_{0}^{4})}$ where ${\displaystyle \epsilon }$ is the surface emissivity and ${\displaystyle \sigma }$ 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:
   • DFlux - general heat flux, enter the Surface Heat Flux in Watts per surface area (W/m^2)
   • Convection (default) - convective heat flux, enter the desired Film Coefficient and Ambient Temperature
   • introduced in 1.0: Radiation - radiation heat flux, enter the surface Emissivity and Ambient Temperature

Notes

• The heat flux load uses the following CalculiX cards depending on the selected mode:
  • *FILM for Convection
  • introduced in 1.0: *RADIATE for Radiation
  • *DFLUX for DFlux