# Parameters for Equation

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• Last Post 02 October 2018
SvenPG posted this 26 September 2018

Hello,

i try to find something by search but no answer could help me with my (little) Problem.

I have a thermal simulation and want to give the convection by an equation.

The equation is 5,67*10^(-08)*(T^4-22^4) but i don t find the right parameter for the Temperature.

Can someone please help me out with the right parameter or where to find it? Would be much appreciated!

Cheers

Sven

kkanade posted this 26 September 2018

Hello,

I assume you are talking about thermal boundary condition for wall where you want to define convection. Please correct me if I am wrong.

You will have to use udf for that. You can try define_profile macro for it.

Regards,

Keyur

pgl posted this 26 September 2018

Hi Sven,

If you are performing a thermal analysis using ANSYS Mechanical (MAPDL), then you can apply convection as surface loads with surface effect elements (SURF151,SURF152). More specifics, such as how the film coefficient can be calculated empirically using the KEYOPT(7) = 1 option are in our online help here.

You can also  modify film coefficients applied by the SFE command via a user subroutine USERCV. This will allow you to modify the film coefficient as a function of both temperature and location if desired. i.e. Plug in your equation.

Here's a really nice example tutorial from our Chanel Partrner DRD. Convection loads are covered at 5:48.

If you need an even higher fidelity solution, then you can enclose the structure in a fluid and perform a conjugate heat transfer simulation in ANSYS Fluent.

Does this information help?

SvenPG posted this 01 October 2018

Thanks for the first tips guys. Is it possible to not use ANSYS Fluent for this? My current model is on Ansys Workbench 18.0.

I inserted a picture here. Same as for my amperage i d like to insert an equation for the konvektion. therefore i need the parameter for temperature. Is it possible or do i need to rethink my model?

Cheers Sven

Kremella posted this 02 October 2018

Hello Sven.

Please see if you can use the options under the Film coefficient to resolve your issue. Let me see if I can post a screenshot soon which might help you.

Best,

Karthik