[Dronzer]

Hi everyone,

I am trying to reduce the flow non-uniformity at exit of a manifold by certain modifications in the geometry. Please see the figure attached (are not real geometries, but similar).

In Case 1, I plotted the uniformity index at the pressure outlet which comes around 0.3 (I feel that it is realistic based on the visual examination of velocity contour).

In Case 2 I extended the geometry by replacing the pressure outlet by porous jump boundary and moving the outlet further downstream. In this case, my uniformity index at the porous jump boundary is almost 1!

Can somebody please explain this?
Thanks in advance.

[LuckyTran]

The porous jump is like putting in a flow conditioning screen. The flow resistance or pressure drop is higher with higher velocity (actually velocity squared) so that it has a tendency to make the flow more uniform.


If you want to isolate and quantify the impact of the porous jump vs the exit extension, then you can run another case with the same extension without the porous jump.

[Dronzer]

Originally Posted by LuckyTran

The porous jump is like putting in a flow conditioning screen. The flow resistance or pressure drop is higher with higher velocity (actually velocity squared) so that it has a tendency to make the flow more uniform.

Thanks LuckyTran,
So, are you saying that it is not advisable to measure flow uniformity at a porous jump boundary because of the approximations used in it?

Please let me know.
Sorry if I am replying late.