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-   -   Piecewise function to model time-dependant BC (http://www.cfd-online.com/Forums/cfx/22400-piecewise-function-model-time-dependant-bc.html)

Ramses Galaz April 5, 2006 02:03

Piecewise function to model time-dependant BC
 
Hi

I am in the need to model the flow of blood passing through the coronary arteries. The inlet BC should be pressure driven by a typical Aortic Pressure Waveform which is a very oddly shaped function of Pressure vs. Time as some parts are linear and some quadratic or higher order.. it would be more accurate to model it as a piecewise function.

I need to know how to define piecewise functions in CEL expressions to model the time-dependant pressure at the inlet for this transient analysis.

Thanks


TB April 5, 2006 02:09

Re: Piecewise function to model time-dependant BC
 
1)Make use of the step function. You can turn on/off an equation on a particular time range.

2)Just another suggestion. Create a 2D data with time & pressure and then import it to Pre using User Function.

Ramses Galaz April 6, 2006 10:00

Re: Piecewise function to model time-dependant BC
 
Thanks

It seems that your 2nd suggestion was better and quicker..



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