Hi all,

I am working on a system comprised of two triangular ducts intersecting each other at 90 degrees. There are two inlets and two outlets. At the intersection the flow gets diverted and a fraction of the flow coming from one inlet (say inlet 1) goes straight (outlet 1) and another fraction bends at 90 degrees and goes to outlet 2 . Same thing happens to flow from inlet 2.

How to calculate the total pressure drop for this system.

Regards, Swapnil.

I guess that the difference of a volume average of the total pressure at the outlet and inlet could give the answer. (mass average will do if the flow is incompressible)

Hi, Jan:

Did you compare the simulation results with real case? I compared the pressure drop. It seems the CFX results are smaller than that of regular method. fly

Hi, Fly:

I found the same result with you. And If I refine the mesh, the result even become smaller. Could you find the explaination from theory in books?

Hannah

Hi fly and Hannah liang ,

are you people working on triangular ducts?

I would be surprised if the values was exactly the same. There are some uncertainities in both measurements and numerical results. I know it is very difficult to get exact numbers when looking for the pressure drop. I have had some succes with predicting pressure drop when using higher order differencing, double precision and doing a grid independency investigation and calculating an estimate of the pressure drop from a Richardson extrapolation of the pressure drop obtained with the three grids. Regards Jan

Hi, Jan:

I agree with your on the pressure drop for measurements and numerical results. But I think they should be the same on some extend. Could you share your success results with me.

Thanks

SXF

Dear sxf, You state that "they should be the same on some extend". I do agree with you, what could I else ). But when will you say you are satisfied, 5% or 10% or 20% etc. What kind of accuracy should be expected from a numerical code with many assumptions and with many constants based on old experiments with an accuracy on???. I remember once a paper with different test cases where several numerical codes was investigated, but I do not remember the exact values , but one should not be surprised if there are some deviations. Regards Jan