Change default density

Submitted by rqwang on Mon, 05/23/2011 - 20:09

Hi all,

I found the default density is 1. Could anyone tell me how to change it to 1000 (for water)?

Thanks.

rq

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cgoniva's picture

cgoniva | Tue, 05/24/2011 - 14:13

Hi!

From CFD side the solver is incompressible and thus the whole momentum balance is divided by rho. Thus you end up with a kinematic viscosity instead of dynamic and a modified pressure (check the units of p field).

So there is actually no direct density in the flow solver.

Further an higher fluid density would result in a buoyancy force of the particles. There were already some posts on how to implement buoyancy.

Cheers,
Chris

rqwang | Tue, 05/24/2011 - 19:02

Hi Chris,

Thanks for your comment.

Finally, I figured out the seemingly correct way to simulate particle settling in water:
Times drag and Buoyancy by 1000 (to make sure correct force is used in DEM)
and divide Ksl by 1000 (to make sure correct momentum is transfered to continuous phase)

The results so far looks right. I will try to upload my file if necessary.

Thanks.

rq