[Fasouras]

Hi guys

i am analyzing a 3d hydrofoil in ansys fluent 19.2 academic and for somw reason after 20 iterations i am getting the message of reverse flow in xxx faces in pressure outlet 6

I ve tried every solution available like changing from pressure outlet to outflow or mass outflow or even i ve tried to move outlet further away from the airfoil (right now my chord is 1m and the domain is 10m ) i ve tried to change the model ( i am using SST k-omega) but the message remains. I have even placed gauge pressure at the outlet in order to suck out any turbulence causing the reverse flow but nothing.

I dont know if this is the main issue but the solution after one point does not converge and goes high up. (pictures attached)

Any opinion on the matter?

[subhankarnits]

Can you show residual image?

[LuckyTran]

These are common warnings and not necessarily anything going wrong here. The only real issue is the solution not converging after 10000 iterations.

It's either your boundary conditions are completely wrong, your initialization was crap, or your mesh is absolute garbage. I would investigate in that order.

You could also remove the airfoil, try just a box to see if you can get a result with this simple setup. Build up some experience.

[Fasouras]

Originally Posted by LuckyTran

These are common warnings and not necessarily anything going wrong here. The only real issue is the solution not converging after 10000 iterations.

It's either your boundary conditions are completely wrong, your initialization was crap, or your mesh is absolute garbage. I would investigate in that order.

You could also remove the airfoil, try just a box to see if you can get a result with this simple setup. Build up some experience.

Hi sir
finally me solution converged somehow but the reverse flow problem remains, My mesh is fine and i think the boundary are also fine as shown in the pictures attached.

I get the cl=1.65 cd=0.3 at 8 degrees..

Is that ok for a naca0012?

[Fasouras]

Originally Posted by subhankarnits

Can you show residual image?

hi sir

here are the residuals you ve asked


Thank you in advance

[piprus]

Sorry for asking silly (little off-topic) questions, but is the idea behind meshing the airfoil itself?

BTW. I see some inconsitencies:
1) In the velocity-inlet, you set 4 m/s while in the initialization it is given 2 m/s
2) The backflow my came also due to pair of inlet-outlet conditions. Try pressure-inlet and pressure-outlet (or far-field if it still exists).

/Piotrek