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Old   January 11, 2010, 11:51
Default Question about UDS equations
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I have a user-defined v2-f turbulence model that uses 4 transport equations, for k, e, v2, and f. For that model, I have defined source equations using DEFINE_SOURCE, and I have turned on their respective equations in the GUI (SOLVE - CONTROLS - SOLUTION.)

I have another model that uses user-defined Reynolds stresses. Those are stored as UDSs, but there are no source equations. Instead, they're defined inside of a DEFINE_ADJUST macro.

My question is this: do I have to turn on the equations in the SOLVE - CONTROLS SOLUTION window for UDS 4, 5, 6, and 7 (the user-defined Reynolds stresses)? I'm thinking that since there's no source equation for them, there's no need to turn them on in the GUI.

Thanks in advance.
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Old   January 11, 2010, 13:02
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I guess I should post an example.

Here's how the k equation is defined:

DEFINE_SOURCE(k_source, c, t, dS, eqn)
real source;

dS[eqn]=- C_R(c,t)*C_R(c,t)*C_MU*C_UDSI(c,t,V2)/C_UDMI(c,t,0);
source=C_UDMI(c,t,3) - C_R(c,t)*C_R(c,t)*C_MU*C_UDSI(c,t,V2)*C_UDSI(c,t,K )/C_UDMI(c,t,0);

return source;

And here's how one of the Reynolds stresses is defined:

(...other code...)
C_UDSI(c,t,R_11)= -2.0*cmu1*C_UDSI(c,t,V2)*T1*S11 + 2./3.*C_UDSI(c,t,K)
( cmu2*(S11*W11+S12*W21+S13*W31+S11*W11+S12*W21+S13* W31) - cmu3*(S11*S11+S12*S12+S13*S13-1./3.*S) );
(...other code...)
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