# total pressure change in a pipe flow

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 February 5, 2002, 20:16 total pressure change in a pipe flow #1 Im Guest   Posts: n/a hi everybody. I have been solve pipe flow with orifice. It's very simple problem. The pipe size is L=50m, D=1.0m. It has orifice at L=10m. As everybody knows, the recirculation region occured right after orifice. Because of these recirculating flow, the total pressure dropped suddenly. Now, My problem is that. The average total pressure at around orifice is lower than outlet average total pressure. Is it possible ? As I know, The static pressure at recirculation region is possibly lower than outlet pressure. Decreased static pressure can be increased as dynamic pressure decrease. but the total pressure never can increase without any additional energy. What is wrong? The solution of fluent or my thought that the total pressure never can increased without any addtional energy. If my idea is wrong, please let me know the mechanism of total pressure gain. thanks in advance.

 February 6, 2002, 09:46 Re: total pressure change in a pipe flow #2 hervé Guest   Posts: n/a Make sure that you are using the so-called "mass-weighted" averaging. If not, try it, you should see a decrease in the so-averaged total pressure.

 February 6, 2002, 12:50 Re: total pressure change in a pipe flow #3 Amadou Sowe Guest   Posts: n/a What fluid material are you using?

 February 6, 2002, 19:07 Re: total pressure change in a pipe flow #4 Im Guest   Posts: n/a I tried all kinds of average method. vertex, facet, mass weighted etc... As change averaging method, the magnitude of total pressure changed, but there is no change in the tendency.

 February 6, 2002, 19:09 Re: total pressure change in a pipe flow #5 Im Guest   Posts: n/a I used air. I just change the density and viscosity. density = 0.82kg/m^3, and viscosity = 0.1cp

 February 23, 2017, 08:55 #6 New Member   Jittanakatti Join Date: Nov 2015 Location: Bangalore Posts: 4 Rep Power: 10 It looks like due to wake there is a vacuum next to sudden expansion or the orifice, which is causing the total pressure decrease refer below link http://www-mdp.eng.cam.ac.uk/web/lib...is/node55.html