FEM ConstraintHeatflux: Difference between revisions

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{{Docnav
|[[FEM_ConstraintInitialTemperature|Constraint initial temperature]]
|[[FEM_ConstraintTemperature|Constraint temperature]]
|[[FEM_Workbench|FEM]]
|IconL=FEM_ConstraintInitialTemperature.svg
|IconR=FEM_ConstraintTemperature.svg
|IconC=Workbench_FEM.svg
}}

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{{GuiCommand
{{GuiCommand|Name=FEM ConstraintHeatflux|MenuLocation=Model → Thermal Constraints → Constraint heatflux||Workbenches=[[Fem Workbench|FEM]]|Shortcut=|SeeAlso=[[FEM_tutorial|FEM tutorial]]}}
|Name=FEM ConstraintHeatflux
|MenuLocation=Model → Thermal boundary conditions and loads → Heat flux load
|Workbenches=[[FEM_Workbench|FEM]]
|SeeAlso=[[FEM_tutorial|FEM tutorial]]
}}


==Description== <!--T:2-->
==Description== <!--T:2-->


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This constraint specifies film heat transfer of a surface at temperature ''T'' and with a film coefficient ''h'' to the environment or sink at temperature ''T<sub>0</sub> ''. The convective heat flux ''q'' will satisfy: '''''q = h(T -T<sub>0</sub>)'''''
By default, defines a convective heat flux load on a surface at a temperature <math>T</math> with a film coefficient <math>h</math> and with the environment (sink/ambient) temperature <math>T_{0}</math>. The convective heat flux <math>q</math> will satisfy: <math>q=h(T-T_{0})</math>. Optionally, can also define a regular surface heat flux load.


==Use== <!--T:3-->
<!--T:15-->
{{Version|1.0}}: Can be also used to define a radiation heat flux on a surface. It satisfies: <math>q=\epsilon \sigma(T^{4}-T_{0}^{4})</math> where <math>\epsilon</math> is the surface emissivity and <math>\sigma</math> is the Stefan-Boltzmann constant.

==Usage== <!--T:3-->


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# There are several ways to invoke the command:
#Click on [[Image:FEM ConstraintHeatflux.png|32px]] or choose {{KEY|Model}} → '''Thermal Constraints''' → {{KEY|[[Image:FEM ConstraintHeatflux.png|32px]] Constraint heatflux}} from the top menu.
#* Press the {{Button|[[Image:FEM_ConstraintHeatflux.svg|16px]] [[FEM_ConstraintHeatflux|Heat flux load]]}} button.
#Select in the 3D-view the surface(s) the constraint should be applied to.
#* Select the {{MenuCommand|Model → Thermal boundary conditions and loads → [[Image:FEM_ConstraintHeatflux.svg|16px]] Heat flux load}} option from the menu.
#Enter the desired surface temperature, film coefficient and environment temperature.
# Click the {{Button|Add}} button. In the [[3D_view|3D view]] select the face(s) on which the heat flux load should be applied. Optionally, click the {{Button|Remove}} button to remove the selected faces from the selection list.

# Choose the heat flux type and specify its parameters:
==Limitations== <!--T:4-->
#* ''Surface Convection'' (default) - convective heat flux, enter the desired ''Film coefficient'' and ''Ambient temperature''
#* {{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== <!--T:5-->
==Notes== <!--T:5-->


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* The heat flux load uses the following CalculiX cards depending on the selected mode:
#The constraint uses the *FILM card in CalculiX. The heatflux constraint is explained at http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node203.html
** [http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node203.html *FILM] for the ''Surface Convection''
** {{Version|1.0}}: [http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node234.html *RADIATE] for the ''Surface Radiation''
** [http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node188.html *DFLUX] for the ''Surface heat flux''



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{{Docnav
|[[FEM_ConstraintInitialTemperature|Constraint initial temperature]]
|[[FEM_ConstraintTemperature|Constraint temperature]]
|[[FEM_Workbench|FEM]]
|IconL=FEM_ConstraintInitialTemperature.svg
|IconR=FEM_ConstraintTemperature.svg
|IconC=Workbench_FEM.svg
}}


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Latest revision as of 16:45, 18 May 2024

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

Description

By default, defines a convective heat flux load on a surface at a temperature with a film coefficient and with the environment (sink/ambient) temperature . The convective heat flux will satisfy: . 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: where is the surface emissivity and 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