[N263883A82261]

Hi,

My project is to simulate the internal airflow of a sailplane at wind tunnel conditions using Star CCM+. I used the basics of a tutorial video I found on youtube as my "recipe" and it worked perfectly.

When I finished the model and started the simulation all the residuals fluctuated badly and didn't seem to want to stabilize after 600 iterations. I created a new simulation using the same model and followed the exact same "recipe" as the previous one, and the residuals started stabilizing after 200 iterations.

I asked my Professor about it and he said that it had happened to him a lot as well. How do I know that the simulation is safe to use if the same thing shows two clearly different results?

Settings used:
Mesh: Surface wrapper, surface remesher, trimmer and prism layer mesher.
Physics: Steady, gas, segregated flow, constant density, turbulent, K-Omega turbulance, three dimensional.

Can one of these settings change the outcome of a simulation even if everything else is the same?

[pswpswpsw]

Originally Posted by N263883A82261

Hi,

My project is to simulate the internal airflow of a sailplane at wind tunnel conditions using Star CCM+. I used the basics of a tutorial video I found on youtube as my "recipe" and it worked perfectly.

When I finished the model and started the simulation all the residuals fluctuated badly and didn't seem to want to stabilize after 600 iterations. I created a new simulation using the same model and followed the exact same "recipe" as the previous one, and the residuals started stabilizing after 200 iterations.

I asked my Professor about it and he said that it had happened to him a lot as well. How do I know that the simulation is safe to use if the same thing shows two clearly different results?

Settings used:
Mesh: Surface wrapper, surface remesher, trimmer and prism layer mesher.
Physics: Steady, gas, segregated flow, constant density, turbulent, K-Omega turbulance, three dimensional.

Can one of these settings change the outcome of a simulation even if everything else is the same?

I am sorry that you must tell what is difference between your two simulations. It seems like that you want to say you follow the same steps exactly but two different results.

If you are telling what you were doing, and they are truth, you had better tell the New York Times that 'Star CCM+ is cheating everyone of us'.

I suggest you check it again.

Good luck,
Shawn