source term udf

tas38 · August 14, 2009, 09:54

I am trying to write a udf that adds a momentum source term.

The source term is written in terms of vorticity and vorticity magnitude. As I cannot explicitly extract vorticity and operators such as grad are not available, does anyone have suggestions as to how to write this udf?

consider for example that the source term is grad(abs(vorticity))/(abs(grad(vorticity)){cross}(vorticity)

where vorticity is the vorticity vector and {cross} indicates cross product

tstorm · August 14, 2009, 11:44

FLUENT stores gradients for user-defined scalars. So, you might try storing those terms as user-defined scalars (i.e., C_UDSI(c,t,0) = vorticity(c,t) ) and then accessing the gradient with C_UDSI_G(c,t,0).
Hope that helps!

August 14, 2009, 09:54	source term udf	#1
tas38 Senior Member Troy Snyder Join Date: Jul 2009 Location: Akron, OH Posts: 220 Rep Power: 19	I am trying to write a udf that adds a momentum source term. The source term is written in terms of vorticity and vorticity magnitude. As I cannot explicitly extract vorticity and operators such as grad are not available, does anyone have suggestions as to how to write this udf? consider for example that the source term is grad(abs(vorticity))/(abs(grad(vorticity)){cross}(vorticity) where vorticity is the vorticity vector and {cross} indicates cross product

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
gradient source term UDF	ak6g08	Fluent UDF and Scheme Programming	0	July 9, 2009 07:37
UDF - Source Term Question	Jacques	FLUENT	0	December 8, 2008 14:40
DxFoam reader update	hjasak	OpenFOAM Post-Processing	69	April 24, 2008 02:24
DecomposePar links against liblamso0 with OpenMPI	jens_klostermann	OpenFOAM Bugs	11	June 28, 2007 18:51
UDF Source Term Units?	Brian	FLUENT	1	October 24, 2005 10:15

August 14, 2009, 11:44		#2
tstorm Member Join Date: Apr 2009 Posts: 78 Rep Power: 17	FLUENT stores gradients for user-defined scalars. So, you might try storing those terms as user-defined scalars (i.e., C_UDSI(c,t,0) = vorticity(c,t) ) and then accessing the gradient with C_UDSI_G(c,t,0). Hope that helps!