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Old   February 22, 2010, 18:37
Default continuity problems
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aek
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hi evrybody

i m new in this forum, and i would to get some advices from anyone for my simulation

i m simulating a 2D axsysimetric furnace chamber 100 m of longer and 5 m of dimaetr (2.5 m from the symetry prb), i have a high velocity injected as boudary conditions (the gaz velocity 70m/s, a primairy air inlet 180 m/s, and a haut secondary air inlet(1310K) with 2.2m/s , in the exit flow i used a pressure outlet as B L and gauge pressure of -310 pascal ,
first , my simulation run well just with the K-omega model and shows a good stability and convergence , other models of turbulence cant works well with my simulation they shows a lot of warnings as turbulent viscosity ratio limited to at cells ...a nd a reversed flow at pressure outlet , i tried a lot of simulation with a different mesh (coarsen and refine mesh) but still the problm persist and especialty the continuity equation, this prob increase when i tried to inject the primairy air swirled

plz help
best regard
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Old   February 27, 2010, 17:11
Default plzzzzzzz help
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aek
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can anyone reply to me plzzzzzz
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Old   March 1, 2010, 01:49
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USMAN
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hi saif,
I will suggest you to change your boundary conditions.If your mesh size is not too large,then make a bigger domain and assign "pressure far field" as a boundary condition.Your problem would be resolved.
If it is not possible,try with some other boundary condition,like mass flow inlet.
Keep on trying,This is not a big issue..
Regards
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Old   March 1, 2010, 18:22
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Quote:
Originally Posted by usman naseer View Post
hi saif,
I will suggest you to change your boundary conditions.If your mesh size is not too large,then make a bigger domain and assign "pressure far field" as a boundary condition.Your problem would be resolved.
If it is not possible,try with some other boundary condition,like mass flow inlet.
Keep on trying,This is not a big issue..
Regards

hi usman naseer

thank u so much for ur reply, i will try ur suggest soon, hope that work, but my question if u can describe me , why my simulation just work with K-omega model , do u think a bC problem?

best regard
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Old   March 2, 2010, 02:53
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Different turbulance models are useful for different applications to model "Reynold stresses".K-w model(turbulant kinetic energy and rate of dissipation energy) is working well in your case because of very high velocity at the inlet (high kinetic energy) and instant dissipation because of the condition imposed at the "outlet".
So it's a better option to use this turbulant model because of the nature of your problem(which can't be changed).
Alongwith K-w model,,I will suggest you to use "density based solver"(coupled solver) instead of "pressure based"(seggregated solver) with suitable velocity-pressure coupling.
Regards
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