Sign of viscous force in the CFDEM coupling

Submitted by caalvarez on Fri, 05/31/2019 - 01:09

Dear Users,

Writing a description of the equations of CFDEM coupling, I noticed that the viscous force is included on DEM side as

-div(tau)*Vp

I did not understand why the minus (-) sign was included, considering that the forces in the particle equation are on the right side. Please, can anyone help with this question?
Best regards,

Carlos

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caalvarez | Mon, 06/03/2019 - 22:39

Dear Users,

Any idea about this question? Thanks for your help and time.

Cheers,
Carlos