# problems with pressure in a microchannel

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 September 19, 2014, 16:11 problems with pressure in a microchannel #1 New Member   Jess Join Date: Sep 2014 Posts: 3 Rep Power: 8 Hello everybody1 I'm simulating a micro-channel with air and water inside using VOF in Fluent, the solution and the phases looks good after converge. I have two phases and mass conservation, but the pressure doesn't looks good, there is no pressure drop and pressure at the inlet is lower than in the exit. Somebody know or have an idea why is this happening? Thanks in advance

 September 21, 2014, 02:30 #2 Member   Sa.Baraty Join Date: Apr 2013 Location: Iran Posts: 50 Rep Power: 9 hi in fluent pressure is relative.you must focus on difference of pressure between inlet and exit. __________________ thanks

 September 24, 2014, 01:13 #3 New Member   Jess Join Date: Sep 2014 Posts: 3 Rep Power: 8 Thank you Sara22 . But can you specify relative to what? relative to the other fluid?

 September 24, 2014, 05:06 #4 Member   Sa.Baraty Join Date: Apr 2013 Location: Iran Posts: 50 Rep Power: 9 only between inlet and exit of fluid domain. for example after solution pressure @ inlet be -4500kpa and pressure @ outlet be+100Kpa. this value are not quotes pressure @ inlet and outlet.the difference of them quotes that the pressure drop of system.(4600Kpa) __________________ thanks

September 24, 2014, 05:31
#5
Senior Member

Join Date: Nov 2013
Posts: 1,758
Rep Power: 22
I don't understand this:
Quote:
 there is no pressure drop and pressure at the inlet is lower than in the exit
Just as any real number, the pressure drop can be positive, zero or negative. What is it in your case? The first part of the quoted sentence suggests it is zero, the second part suggests it is negative.
(Of course positive is what you want, so both are bad, but to be able to solve your problem we first need to understand it.)

 September 24, 2014, 15:57 #6 New Member   Jess Join Date: Sep 2014 Posts: 3 Rep Power: 8 When I check the contours of static pressure I have negative number at the inlet and outlet is always zero, when I check the results of static pressure I have an negative number (totals), but when I plot the static pressure I have positive static pressure at inlet and always zero at the outlet. I'm not sure If I'm doing something bad or if ansys has a tricky system. Of course I want to have positive number at inlet and zero at outlet. Thanks Sara22 and pakk for your answers I hope you can continue help me

 Tags drop pressure, fluent, inlet