[Suman Sapkota]

Dear Gert,

I checked on the conditions. It seems to be fine. I re-run the simulation and found out that the difference is only due to the "Moving (hub+ shroud) and Blade" boundary (Attached figure name: 11) being segregated in this case. When they are segregated I put restitution coeff. in moving boundary as 1. So, the particle (if collides) bounces back. And for the blade "as per you suggestion" i put it 0 to select it as outlet region in the post process. If I do not segregate moving and blade domain, i cannot put the restitution coeff. value in blade and that makes me unable to select blade as the outlet boundary in post. The difference in efficiency is due to the "torque" as i have to add?? (since the blade lies inside the "moving" [hub+shroud] boundary in my view) the torque by both moving (hub+shroud) and blade domain.

Previously, for higher efficiency I combined blade+hub+shroud as "Moving boundary"(figure number 12). That gives me a different torque with higher efficiency. But I can only put the restitution coefficient in moving boundary in this case. That again prevents me from selecting blade as outlet region in post since the restitution coeff. is supplied for whole moving boundary (hub+shroud+blade). Is there a way to solve this problem? i hope you understand why I had to change the setup for creating unique boundary for blade. Is there another way to do this that allows me to track particle hitting the blade?

The inlet conditions are same with no counter rotation except for the stall (i think it is normal) above the blade. The rotating boundary is the hub+shroud+blade. So, basically except inlet and outlet every domain is rotating in clockwise direction.

[Gert-Jan]

Somewhere it stops helping you using text and screenshots. I think you'd better send your case or ask a supervisor from your department.

[jbww]

Originally Posted by usamaperwez

When i made two export results in Output control, it worked. It seems to be a bug.

I found another interesting thing in my case. My problem consist of a serpentine channel which contain bends. For that, you need to activate Schiller Naumann model and then particle started to follow the bend path otherwise it was hitting the wall and bouncing back.

Thanks alot for the help.
Best of luck !

The same bug happen to me, or it's actually not a bug of the program.
In the CFX Theory Guide -> 6. Particle Transport Theory, the calculation of particle position is given as
,
where the superscript o and n refer to old and new values, and is the particle velocity.
The particle velocity is updated as

where is the particle mass, and is the total force exerted on the particle.
Thus if drag force or other forces are set to "none", the particle velocity would not be changed.
By setting drag force only with a large drag coefficient and a small particle diameter, the particle velocity approximates the fluid velocity at the same position.
This thread gives the same suggestion: Massless Particle Tracking
You set a Schiller Naumann drag force with a small particle diameter, achieving similar effect.