Convergence of Steady State Turbulent Airflow
I'm learning CFD and have a model of a vacuum nozzle. The goal is to get a uniform ability to pickup debris over an 18 inch wide swath. I have a half model since the hose pulls air from the center of the nozzle. This design has two plates with holes in the mouth of the nozzle to break up the flow and avoid a very high velocity at the center of the mouth that occurs without the two plates.
I have a surface at the center of the large holes to plot the velocity.
There is a second plane though the center of the small holes.
Here is a view of the mesh. I have 12 inflation layers on all the surfaces on the inside of the nozzle, and the floor that the nozzle throat is suspended 5 mm above.
The inlet are the sides of the enclosure a good distance from the nozzle. The outlet is a pressure outlet at -1000 Pa.
My question is on convergence. Here is the convergence plot.
The residual value for continuity is 3e-2 which is my main concern. The residual values for x,y,z velocity are 3e-4 which may be acceptable.
What should I do to confirm that the above model is properly converged?
It might be that the skewness element quality is insufficient.
On similar model, I was able to get the residual value for continuity below 1e-7. That only had 3 layer of inflation.
On this model, I kept working on element quality until the skewness was < 0.86.