# Monitoring Pressure Drop

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 April 17, 2016, 04:44 Monitoring Pressure Drop #1 Member   Rahul Join Date: Sep 2015 Posts: 33 Rep Power: 3 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.

 April 17, 2016, 06:31 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,646 Rep Power: 105 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

 April 17, 2016, 08:42 #3 Member   Rahul Join Date: Sep 2015 Posts: 33 Rep Power: 3 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.

 April 17, 2016, 08:48 #4 Member   Rahul Join Date: Sep 2015 Posts: 33 Rep Power: 3 the difference in dynamic head between inlet and the outlet is 4.700KPa-this is result given in the literature

 April 20, 2016, 02:19 #5 New Member   Rokson K Mathew Join Date: Feb 2016 Posts: 8 Rep Power: 3 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!

 April 24, 2016, 12:06 #6 Member   Rahul Join Date: Sep 2015 Posts: 33 Rep Power: 3 Thank you so much for your inputs Mathew Cheers!

 Tags cfx, muffler, pressure drop

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