# Caedium and Moving mesh

Submitted by navvabk on December 22, 2011 - 00:35

Hello,

Thanks a lot!

Can Caedium deal with moving mesh? Is it possible to model water flow inside a turning swirl water turbine?

## No moving mesh

Not at the moment. For more on what Caedium can and can't do see the the RANS Flow add-on product page.

## Thanks a lot for your reply.

Thanks a lot for your reply.

for modeling the small scale water turbine:

1) Actually I decided to rotate the outer boundary (housing) by introducing angular velocity and fix the blade itself. The results seems converged (though at high iterations fluctuation in residual can be seen). I just wonder about the pressure contour. Its range is very small (-0.005,0.005)? I assume that the pressure is gauge pressure and in Pa.

2) Since the Housing is rotating then zero gradient for velocity at outlet should be nonphysical (outlet in an end for the cylindrical housing). I tried other boundary conditions for outlet. The extrapolated outlet condition made no difference and the fixed flow rate outlet boundary is not working.

I appreciate your reply.

## Missing Coriolis effect

Your simulation will be missing the Coriolis force - the tendency of the water (due to its mass) to travel outwards while spinning.

Yes, for incompressible flow the simulation uses/reports gauge (or relative) pressure.

Given the non-physical nature of your simulation I'm not sure how you should treat the outlet.

Whether the fixed volume flow rate for the outlet will work depends on your inlet(s). If you specify a flow rate or velocity at your inlet(s) then fixing the volume flow rate will likely fail unless you have an exact match. However, even with an exact match it will likely fail due to rounding errors.

## Thanks a lot for your

Thanks a lot for your reply.

Is it possible to add Coriolis term to momentum equation? I mean, is there any kind of UDF or source code accessibility with Caedium?

## MRF

No, but a future version of Caedium will provide Moving Reference Frames (MRF).