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-   -   User Function (http://www.cfd-online.com/Forums/star-ccm/86979-user-function.html)

racerdude777 April 7, 2011 16:04

User Function
 
I'm modeling a 3-D wing in a wind tunnel and am looking to oscillate the flow direction in a sinusoidal fashion. I am looking to use a simple user function to accomplish this but Star-CCM+ can't compile it. Can somebody take a look and shed some light on whats wrong with it? Thank you.

First Code:
($Time > 0) :
$$Velocity[0] = 24.218*COS*(0.2094395+0.174533*SIN*((0.2079*$Time) ));
$$Velocity[1] = 24.218*SIN*(0.2094395+0.174533*SIN*((0.2079*$Time) ));
$$Velocity[2] = 0;

Second Code:
($Time > 0)? [24.218*COS*(0.2094395+0.174533*SIN*((0.2079*$Time) )), 24.218*SIN*(0.2094395+0.174533*SIN*((0.2079*$Time) )), 0] : [0,0,0])


racerdude777

f-w April 7, 2011 17:17

Try:

[($Time > 0) ? 24.218*cos(0.2094395+0.174533*sin(0.2079*$Time)) : 0, ($Time > 0) ? 24.218*sin(0.2094395+0.174533*sin(0.2079*$Time) ) : 0, 0]

abdul099 April 14, 2011 02:58

$$Velocity[x] with x = 0,1,2 (from the first code) adresses the velocity field generated by the solver. You can not assign any values to one of the default field functions, so the statement "$$Velocity[0] = " can not work.
In general, your second code should work, but there are some * too much between the sin and cos functions and the following brackets. Even on your calculator, you don't type "sin * (5*PI)", you type sin(5*PI).

Try
($Time > 0)? [24.218*COS(0.2094395+0.174533*SIN((0.2079*$Time) )), 24.218*SIN(0.2094395+0.174533*SIN((0.2079*$Time) )), 0] : [0,0,0])


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