[quattro123]

Hello, since i dont know exactly how the pressure velocity couplings influence the solution, i tried a experiment.

My test case was a lid-driven cavity where only the lid is moving (the top of the quader) in x-direction.


Now i simulated the same case with the three different coupling algorithms:

SIMPLE, SIMPLEC and PISO.


Then i plotted the velocities of x and y direction on both x and y middle axis to compare them.



The thing is the iteration of the lid.
From a fluent tutorial I have the information to iterate from neither the fluid nor the lid, just put a small value for the x velocity and a very small value for the y velocity.


I did it, i followed the tutorial very carefully and all of my velocity plots look very different. I thought thats okay.




Now i did also another iteration, where i initalized from nothing. i didnt select any item or entered any initial velocity in the initialize window and i iterated.
I thought this makes no chance, except that it will need much more iterations. But then i plotted all the velocities again for the different couplings and i realized that all of them are NEARLY the same, they are very very close the same.





So, which one is the right way to do that?
I guess the velocity couplings have to be different, dont they?

Or will i see just a difference when i use a coarse mesh?

Maybe one can shortly introduce me the basics/difference of the 3 algorithms? i already read the fluent manual, but i understood nothing of this.




Kind regards!