FEM ConstraintHeatflux

Constraint initial temperature

Constraint temperature

FEM

FEM ConstraintHeatflux
Menu location
Model → Thermal boundary conditions and loads → Heat flux load
Workbenches
FEM
Default shortcut
None
Introduced in version
-
See also
FEM tutorial

Solvers
CalculiX, Elmer

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.

introduced in version 1.0: 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
   • introduced in version 1.0: 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
  • introduced in version 1.0: *RADIATE for Surface Radiation
  • *DFLUX for Surface heat flux

Constraint initial temperature

Constraint temperature

FEM

FEM

• FEM Analysis

• Materials: Solid, Fluid, Nonlinear mechanical, Reinforced (concrete); Material editor

• Element geometry: Beam (1D), Beam rotation (1D), Shell (2D), Fluid flow (1D)

---

Constraints

• Electromagnetic: Electrostatic potential, Current density, Magnetization

• Fluid: Initial flow velocity, Initial pressure, Flow velocity

• Geometrical: Plane rotation, Section print, Transform

• Mechanical: Fixed, Displacement, Contact, Tie, Spring, Force, Pressure, Centrif, Self weight

• Thermal: Initial temperature, Heat flux, Temperature, Body heat source

• Overwrite Constants: Constant vacuum permittivity

---

• Mesh: Mesh Netgen, Mesh GMSH, Mesh boundary layer, Mesh region, Mesh group, Nodes set, Mesh to mesh

• Solve: CalculiX Standard, Elmer, Mystran, Z88; Equations: Deformation, Elasticity, Electrostatic, Electricforce, Magnetodynamic, Magnetodynamic 2D, Flow, Flux, Heat; Solver: Solver control, Solver run

• Results: Purge, Show; Postprocessing: Apply changes, Pipeline from result, Warp filter, Scalar clip filter, Function cut filter, Region clip filter, Contours filter, Line clip filter, Stress linearization plot, Data at point clip filter, Filter function plane, Filter function sphere, Filter function cylinder, Filter function box

• Utilities: Clipping plane, Remove clipping planes, Open FEM examples; Mesh clear, Mesh display info

---

• Additional: Preferences; FEM Install, FEM Mesh, FEM Solver, FEM CalculiX, FEM Concrete; FEM Element Types

User documentation

• Getting started
• Installation: Download, Windows, Linux, Mac, Additional components, Docker, AppImage, Ubuntu Snap
• Basics: About FreeCAD, Interface, Mouse navigation, Selection methods, Object name, Preferences, Workbenches, Document structure, Properties, Help FreeCAD, Donate

---

• Help: Tutorials, Video tutorials
• Workbenches: Std Base, Assembly, BIM, CAM, Draft, FEM, Inspection, Material, Mesh, OpenSCAD, Part, PartDesign, Points, Reverse Engineering, Robot, Sketcher, Spreadsheet, Surface, TechDraw, Test Framework

---

• Addons: Addon Manager, External workbenches, Scripting and macros

---

• Hubs: User hub, Power users hub, Developer hub