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Old   April 17, 2016, 04:44
Post Monitoring Pressure Drop
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Rahul
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I want to simualte air flow pattern in a muffler.For that i will monitor value of pressure drop between the inlet and the outlet
Turbulence Model-SST
Fluid-Air at 25 Degree Celsius

Boundary Conditions:
mass flow rate-inlet-0.2194kg/sec
pressure-outlet-Relative static pressure is set to 0 Pa

I defined a expression in CFX as
areaAve(Pressure)@REGION:INLET-areaAve(Pressure)@REGION:OUTLET
Now what my problem is CFX reports the value of Pressure drop to be 1.2E-08 !!
Could anybody please help me in this regard?

Last edited by raghulvr; April 18, 2016 at 21:18.
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Old   April 17, 2016, 06:31
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Glenn Horrocks
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This is an FAQ: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

Some possibilities:
* What units is the 1.2e-8 in?
* Did you set the flow rate and geometry size correctly?
* What is the dynamic head at the inlet and outlet? Does that explain the difference?
* Otherwise the FAQ lists lots of other issues. Inadequate mesh resolution is the problem in 95% of questions on accuracy in my experience, by the way
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Old   April 17, 2016, 08:42
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Thank you so much for the reply
I have given all the details regarding my simulation

Last edited by raghulvr; April 18, 2016 at 21:21.
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Old   April 17, 2016, 08:48
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the difference in dynamic head between inlet and the outlet is 4.700KPa-this is result given in the literature
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Old   April 20, 2016, 02:19
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Rokson K Mathew
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I would suggest a pressure inlet, mass flow outlet
inlet pressure- 1 atm (101325 Pa)
To monitor pressure drop in the system, Total Pressure would do fine.
(massFlowAve(Total Pressure in Stn Frame )@Inlet - massFlowAve(Total Pressure in Stn Frame )@Outlet)
Try using this expression

Cheers!
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Old   April 24, 2016, 12:06
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Thank you so much for your inputs Mathew
Cheers!
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