SimScale CAE Forum

Pressure and Density solution field blows up


#1

Hi folks…first time poster here…

I am currently working on a transonic flow (around 0.8mach) over a 3d wing case and need help with pressure and density convergence…not sure if they are the correct term, but the problem is basically this…

The analysis takes at high speeds 0.8 Mach, so as not to shock the solver, I have introduced a velocity ramp from 10ms at 0 t to 233 m/s by 2000t. Checking the inlet values, the speed has nicely gradual ramp to its final velocity. The force and moment coefficient also show very nice value…even after 2000t and all the way to the end of the simulation (3000 iterations).

Velocity ramp input.

Forces and Moment coefficient plot (looking smooth no?)

Convergence plot

What the issue is, the pressure and the density readings from the solution fields…while all other variable show “ok” values, (not the smoothest) the pressure and the density have been fully erroneous.

This is the velocity solutions

but this is the density (pressure looks exactly the same)

Everything was fine before it hit 2000 iterations!

…and as expected, the calculated coefficient values from paraview readings were different to the ones provided by the built in…

What could be the cause of this?

Thank you

here is the project, I have made it public. the simulations are in Cruise 2 and 0 degrees.

https://www.simscale.com/workbench/?pid=1804273100703166300&rru=238089d4-fbea-4f1f-9c7d-a31513538cd5&ci=7e9541ad-4277-406e-b5ef-6995156d01fe&ct=SOLUTION_FIELD&mt=SIMULATION_RESULT


#2

Hi @scha!

@CFD-SQUAD, can you help our user here and see what he could optimize?

Best,

Jousef