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-   -   Writing a step function in transient thermal problems (https://www.cfd-online.com/Forums/ansys/105365-writing-step-function-transient-thermal-problems.html)

kolvos July 28, 2012 15:56
Writing a step function in transient thermal problems
 
Hi,

I've been trying to write a step function that makes my convection coefficient 0 every 6.4 seconds for a period of time of 0.3 secs. Other periods of time I want it to be 25.. I want this to continue indefinitely.

Anyone has ideas? Would really be glad if someone just wrote me the function..

Thanks

flotus1 July 30, 2012 05:59
In fluent you could use a UDF which includes the following
Code:
double time;
double coeff;

time=RP_Get_Real("flow-time");
while(time > 6.7)
{
time = time-6.7;
}
if(time < 6.4) coeff = 25.0;
else coeff = 0.0;

kolvos July 30, 2012 06:46
Hi and thanks for you feedback.

How should I input this kind of code?
I was meaning to use the "Functions" option under Define Loads..

Thanks again

flotus1 July 30, 2012 08:12
So I see you are using the "transient thermal" node in Ansys workbench.
I don't know if it is possible there have this kind of boundary condition unless you write a table with the values for the whole simulation time.

Personally, I would rather use Fluent or CFX for a transient thermal analysis.

kolvos July 30, 2012 08:23
How can I write a table?

Thanks


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