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CFD MAN November 26, 2002 19:26

Saffman Lift Force
Hallo In the Fluent manual, its writtin as: -- The Saffman's lift force, or lift due to shear, can also be included in the additional force term as an option. The lift force used is from Li and Ahmadi [ 135] and is a generalization of the expression provided by Saffman [ 196]:

(19.2.19) [please see the equation in the manual, V6]

where K=2.594 and d ij is the deformation tensor. This form of the lift force is intended for small particle Reynolds numbers. Also, the particle Reynolds number based on the particle-fluid velocity difference must be smaller than the square root of the particle Reynolds number based on the shear field. Since this restriction is valid for submicron particles, it is recommended to use this option only for submicron particles. ---- My question is, after solving a particulate flow (enabling the saffman lift forc), how can I calculate the saffman lift force at a particular location of the particle trajectory? I know particle size, density, velocity and also fluid velocity, so I know Ur, Cd, Rep, but how do I know deformation tensor along the path of the particles?

Any suggestion would be appreciated.


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