Reverse flow on a Presure outlet

albertolot · March 26, 2010, 20:37

Hey guys
I'm teying to run a simulation of a wing and i made a growth function mesh on it, when i go to fluent there is a msg of a reverse flow on the pressure outlet face. Can some one tell me how to simulate it or how could i mesh the wing in order to get the best results.?
P.S. I'm using Gambit to mesh it.

sega · March 27, 2010, 05:25

There is a good tutorial of an airfoil.
Well, it's not a wing, but you will get a good overview whats important so such an external flow.

thecfduser · March 27, 2010, 07:11

Hi
it is not a problem if u get a reversed flow....
Tell us more about ure outlet position: is it enough far from the wing???? do u have any vortex schedding???

albertolot · March 27, 2010, 12:06

Well the outlet is far enough i think, the thing is that the results that are coming out are not good at all... is good to tell you guys this is a 3D wing.

p.s. thanx for your help.

thecfduser · March 29, 2010, 04:49

well, i dont think the problem is the reverse flow on the pressure outlet ...

are u using steady or unsteady solver?????? wich turbulence model????? wich near wall treatment ?did u verify convergence???? do u have vortex schedding ???? what do u got as results?

albertolot · March 29, 2010, 19:58

Well I'm using a Pressure Based, steady flow solver, I changed the operating conditions turn on the spalart allmaras viscuos model, and i also changed my convergence to 1E-6.
And my results are negative lift negative drag and a moment that is really out of order... if you have any idea of how I can improove my simulating Ill be realy thankfull.

PS. I changed the reference values the area and the temp.

thecfduser · April 1, 2010, 19:09

ure residuals have gone under 10-6????
if yes, i suggest that u use unsteady solver and that u average results then.

heidar · April 2, 2010, 09:54

do u have any problem by the reverse flow?
do u have any divergence in residuals?
if u have not any problem by above-mentioned please go on and don't wait.
in the end boundary u may have some real reverse flow and tiny circulation zone. have u?

March 26, 2010, 20:37	Reverse flow on a Presure outlet	#1
albertolot New Member alberto Join Date: Aug 2009 Posts: 7 Rep Power: 18	Hey guys I'm teying to run a simulation of a wing and i made a growth function mesh on it, when i go to fluent there is a msg of a reverse flow on the pressure outlet face. Can some one tell me how to simulate it or how could i mesh the wing in order to get the best results.? P.S. I'm using Gambit to mesh it.

March 27, 2010, 05:25		#2
sega Senior Member Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 21	There is a good tutorial of an airfoil. Well, it's not a wing, but you will get a good overview whats important so such an external flow. __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

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March 27, 2010, 07:11		#3
thecfduser Senior Member karine Join Date: Nov 2009 Posts: 158 Rep Power: 18	Hi it is not a problem if u get a reversed flow.... Tell us more about ure outlet position: is it enough far from the wing???? do u have any vortex schedding???

March 27, 2010, 12:06		#4
albertolot New Member alberto Join Date: Aug 2009 Posts: 7 Rep Power: 18	Well the outlet is far enough i think, the thing is that the results that are coming out are not good at all... is good to tell you guys this is a 3D wing. p.s. thanx for your help.

March 29, 2010, 04:49		#5
thecfduser Senior Member karine Join Date: Nov 2009 Posts: 158 Rep Power: 18	well, i dont think the problem is the reverse flow on the pressure outlet ... are u using steady or unsteady solver?????? wich turbulence model????? wich near wall treatment ?did u verify convergence???? do u have vortex schedding ???? what do u got as results?

March 29, 2010, 19:58		#6
albertolot New Member alberto Join Date: Aug 2009 Posts: 7 Rep Power: 18	Well I'm using a Pressure Based, steady flow solver, I changed the operating conditions turn on the spalart allmaras viscuos model, and i also changed my convergence to 1E-6. And my results are negative lift negative drag and a moment that is really out of order... if you have any idea of how I can improove my simulating Ill be realy thankfull. PS. I changed the reference values the area and the temp.

April 1, 2010, 19:09		#7
thecfduser Senior Member karine Join Date: Nov 2009 Posts: 158 Rep Power: 18	ure residuals have gone under 10-6???? if yes, i suggest that u use unsteady solver and that u average results then.

April 2, 2010, 09:54	hi	#8
heidar Member heidar jafarizadeh Join Date: Mar 2010 Location: Iran- Tehran Posts: 43 Rep Power: 17	do u have any problem by the reverse flow? do u have any divergence in residuals? if u have not any problem by above-mentioned please go on and don't wait. in the end boundary u may have some real reverse flow and tiny circulation zone. have u?