# MassFlow Function? Absolute MassFlow? Failure in Caclulation

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May 5, 2011, 09:46
MassFlow Function? Absolute MassFlow? Failure in Caclulation
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Hi guys

I posted a similar question a few months ago and I am trying it now again. I have a geometry with 2 Inlets where fluid can go in and out and also one Outlet on the side, where fluid can go in and out. (For a pic see in the attachement)

This is my problem

I want to calculate Percentage of the Massflow which is going inside the domain and coming out.

These are my 3 domoins
Interface_Top
Interface_Bottom
Interface_Side

I created an AbsInt for every Interface Expression:
AbsIntTop = areaInt(Density * abs(Velocity in Stn Frame w))@Interface_Top

I also used the CFX Massflow function for every surface.
MassFlowTop = massFlow()@Interface Top

If the MassFlow result is positive on Top Side (x-y Plane) it means that the Result is that part which is going inside the domain, which means that I can just say:

AbsInt - MassFlow = Fluidpart which is coming out again and not keeping inside

For the Interface_Side I used of course the radial velocity and not the Velocity w!

So these are my results:

AbsInt
AbsInt Interface Top 0,0073
IAbsInt nterface Bottom: 0.0057
AbsInt nterface Side: 0,0155

MassFlow
MassFlow Interface Top: 0,00626
MassFlow Interface Bottom:0,00562
MassFlowInterface Side: 0,0139

Let's do AbsInt - MassFlow for every Inteface.
Delta Interface Top 0,00104
Delta Interface Bottom 0,0001
Delta Interface Side 0,0016

These must be the part of the fluid which is a Loss. So If I sum up e.g.:
AbsInt Interface Top - Delta Interface Top + IAbsInt nterface Bottom - Delta Interface Bottom it should be MassFlowInterface Side

0,0073-0,00104+0,0057-0,0001 = 0,01186 which is NOT MassFlow InterfaceSide = 0,0139

Sorry for the complicated way to explain my question?

Need help! :-)

Thanks
Attached Images
 Velw1.jpg (53.2 KB, 9 views)

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