Learning Forum

[veeramanik]

I am doing a simulation in ANSYS Fluent for an impinging air jet on a flat surface using axisymmetric option. I used the standard k-epsilon model with SIMPLE solver. When I run the simulation, my residuals converged at 0.001. However, there was a reverse flow message during the whole simulation. Is it normal to have reverse flow in the domain?

Thank you.

[Karthik Remella]

Hello Can you post an image of your computational domain? And what are your boundary conditions settings?
If you are seeing some reversed flow at the outlet and if the outlet is really far away from the region of interest, it might be okay. Check the magnitude of the reversed flow by plotting some velocity vectors.
Karthik

[veeramanik]

Hi Karthik
Thanks for your response. I am interested in estimating the wall shear stress on the impingement plate. Though it is 0.20 m long, I am interested in the first 0.02 m (20 mm) since that is the actual size of the plate surface. The reverse flow message appears for pressure outlet ( the top one from the image).
I used k and epsilon for velocity inlet boundary conditions and atmospheric conditions for pressure outlet. The interior and wall are default in Fluent. The k and epsilon values were calculated using equations given in Fluent manual.
Veeramani

[Rob]

Have a look at the flow field, colour contours by x-velocity and alter the scales to highlight positive x-velocity (clip is worth investigating). Also read up on jet entrainment.
Read the theory on the turbulence models: why are you using standard k-e?

[Karthik Remella]

Hello Here are some resources from Ansys Innovation Courses on Impinging Jet that you might find useful.
Karthik