I'm searching for some helpsters, i am a newbie in this software. To my problem: the volumetric model i have created is a part of a hydraulic valve. As boundary conditions i've set a pressure-difference between inlet and outlet. The simulation shows the pressure growth but unfortunately when i try to measure the flow on a plane it shows that there is nearly no flow at all- something like 6E-7 but the pressure seems to be correct.
I have tried to change my flow media from hydraulic oil to water, checked the boundary conditions and so on, but at the moment i am helpless. You can see the project file in my attachments. Sorry for my bad english, i'm a german student.
Greetings and thanks for your help
Solved! Go to Solution.
Try changing the Advection Scheme to 5 (Solve ->Soution Controls -> Advection). We should always do this where we have pressure driven flow.
We cannot view the file you attached, we would require a cfz (support file).
Hello, thank you for a quick reply!
I already tried to use ADV5 it doesn't help unfortunately. The support file is to big sth. about 4 mb, so i can't create an attachment, i'l try to upload it in a different way.
- Extend the inlets and outlets by 5x diameter - having small steps near Boundary Conditions is never a good thing. Ideally we want flow over a BC to only travel in one direction, not swirl
- Run for more than 100 iterations - ideally until CFD converges by itself
- More mesh here might be wise, or simply turn on the Surface and Gap Refinment in the mesh settings (change the Gap Elements in Advanced to 3 - optimum for valves)
It does run fine as it is though, I made no changes and just pressed Solve:
Okay, i have checked it again, i measured the velocity with ctrl+shift on the plane it was a very small value, perhaps it was coming from false measuring.
Could you explain your point 1. about 5x-Diameter rule? Would appreciate!
Ah, that is the problem them. 'ctrl shift' shows results on the solid surface, you just need 'shift' for results on a plane.
The 5x dia is to ensure smooth flow into and out of the analysis, to avoid and recirculation over the boundaries. Using 5 we are pretty much guaranteed this will be the case.