Mei/Saffman lift force vs viscForce

Submitted by evansmuts on Mon, 11/04/2013 - 16:22

Hi

I am getting confused between the Mei/Saffman lift force and the "viscForce". As far as I can tell, they both depend on the fluid velocity gradient. So won't using both the Saffman force and the viscForce include the same effect twice? Or do they act in different directions?

Can anyone explain what the differences are?

Thanks
Evan

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cgoniva's picture

cgoniva | Fri, 11/22/2013 - 14:33

Hello Evan,

while "viscForce" is a force that arises from splitting up momentum exchange term to pressure dependent, fluid stress dependent and "drag like" terms.

To my understanding Saffman lift force is in contrast to that due to finite size of a particle in a spatially non-constant flow field.

To be honest, I did not yet dig too deep into the background of the Mei model.

Cheers,
Chris

rqwang | Fri, 11/22/2013 - 15:58

Hi Evan,

I contributed the original MeiLift code. The purpose is to simulate the lateral force when particle rotates. However, here we have no relative rotation. We just assume particles follow the ambient flow, which means no relative rotation.

Thanks.
rqwang