I am working on establishing a system pressure based on adjustable louvers. To simulate the louvers, I am using a volumeric resistance model with a free flow %. I figure by varying the flow thru value, I can achieve the system pressure I am targeting. However, if I use different free flow values, the system pressure does not change. If I apply a solid, pressure goes way up. If I apply air, system pressure goes way down. If I apply an % free flow value, system pressure changes to a constant value...No matter what % is applied... From 90% to .01%. What am I missing here? I have setup a very simple test part, attached.
Solved! Go to Solution.
Hi Eric,
Thanks for the file (although we only need a CFZ in future if it helps). I just have two points:
Kind regards,
Jon
Jon:
Thanks for the quick response. I'm am on CFD 2014, v 14, and cannot update to 2015. So I've taken your input to refine the mesh of the resistance part, then change the iterations to 300 and went with Advection 5. Still no pressure delta between 90% or 5% resistance. Listed are pre-change and post-hange results (csv attached). Do you have any other ideas? Seems like a fundamental capability that CFD should perform or that I'm not understanding correctly. I'll play with surface resistances next.
Pre-Changes...
Mat System Pressure System Velocity Inlet Pressure Iterations
Alum 0.028900 245.66 0.0278026 100
Air 0.000666 17.41 0.0003625 100
90.00% 0.002025 40.56 0.0017188 100
5.00% 0.002025 40.55 0.0017182 100
Post Changes...
Alum 0.045648 229.512 0.0432426 178
Air 0.000998 19.3044 0.0003511 131
90.00% 0.009667 105.759 0.0090153 132
5.00% 0.009630 105.542 0.0089789 136
Thanks.
-Eric J
Jon:
I converted to the surface resistance method, and now the result appear to be valid. It appears that the volumetric resistance method is not applicable for this situation.
Thanks for your help.
-eric
snapshot of results curve attached.
Hi Eric,
Good to know it is working.
Either approach should be OK, although we need to be sure we have the correct solver settings for each.
Kind regards,
Jon
Can't find what you're looking for? Ask the community or share your knowledge.