[CoP]

Hello everybody,

I'm doing a cfd-simulation on a impeller of a pump and i have some problem with the convergence (as many people befor me ). I already tried some stuff and used the advise postet here in this forum, their were already very helpful!

First some details about my mesh, build with ICEM:
all tri (I decided to use all tri because i have some areas in my geometrie which have very small angles.)
cells ~230k
min Angel 18 (ICEM)
orthogo qual: 4,66*10^-1
cell squish: 5,3310*10^-1
cell equi dis: 5,69*10^-1
Aspect R: 8,37*10^-1
min Exp Ra: 1,74*10^-1 from Fluent

My mesh is a quarter of a disk (impeller) with a orifices. I made periodic conditions, i think they are ok, the mesh display is a complete disc, orth qual isn't 0.

Now the parameters like in Fluent i will discribe everyone.

General: pressure-based, absolute, steady
Model: k-omega-sst
materials: water-liquid, aluminium
cell-cone: rot-orig 0/0/0, rot-axis 0/-1/0 (i dont knwo why i have to choose -1, but with 1 i have orthog qual = 0)
Boundary cond:
- pressure-outlet: 90000pas, vector 0/-1/0
- walls: moving, absolute, rotating, origin 0/0/0, rot-axis 0/-1/0, no slip, wallroughness default
- mass-inflow, ~1,03, 0-1/0
- symmCond: pressure-grad = 0, flow dir 1/0/0
- opera cond: 101325pas, reff-loc: 0/0/0
- reference values: pres 101325pas, temp 293,15K, lenght 4mm (orifices lenght), v=~3ms^-1(based on massflow trough the orifices), ref zone: fluid

Here i got some understanding problems: Reference to what/which zone/point?

solution: coupled, least square cell based, 2nd order, 2nd order, 2nd, 2nd (I started with 2nd, 2nd, 1st, 1st as suggested and switched to 2nd, 2nd)
controls: courantnumber o,5, exRelFac: 0,75/0,75, udr: default
initialization: hybrid, 10it ->10it=~6*10^-8
RunCalc: check everything ok

I already tried modifying the exRelFac. I recognized when i lower the momentumFactor the continuity res will drop. At 0.01 monRelFac i get about 10^-4 to 5 res. But i think its not an satisfying solution because the RelFac ist almost 0.

If anyone has any idea plaese let me know. I'm happy about any ideas.

Thanks in advance!