centrifugal compressor with vaneless diffuser

Hi, 

Which platform you are using Fidelity or Fine and which version?

Hi,

i am using FINE

Hi,

i am using FINE

Yes you can use both at one time. Import as External CAD in Autogrid using Import CAD option. Link the vane and diffuser separately to blade and diffuser

Thank you very much for yor response. I have started them as single row. In the boundary conditions under the solid tab, i split the hub and define imepller hub as rotating and diffuser hub as non rotating. My mesh quality is good and boundary conditions are right too but still i am unable to run the simulation. As soon as simulation starts density and pressure goes to negative. any thoughts on that ?

The vaneless diffuser is axisymmetric? You may want to run a simulation with 0 iterations and check where in the field it is so unphysical that it causes negative density and pressure so rapidly. Check the velocity on the solid walls and the quantities on inlet and outlet to check that it really matches what you needed. The direction of rotation of the vanes is correct?