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-   -   Saffman Lift Force: confused (https://www.cfd-online.com/Forums/fluent/30579-saffman-lift-force-confused.html)

 CFD_MAN November 26, 2002 18:24

Saffman Lift Force: confused

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.

CFD MAN

 CFD_MAN November 27, 2002 12:30

did I ask a difficult question?

Hallo, Did I ask a difficult or stupid question ?

Until now no ansers !!:(

CFD MAN

 Amid Naz November 27, 2002 16:52

Re: Saffman Lift Force: confused

Neiter nor, but actually I have no access to the manual..Anyway, to post a question in this forum dont expect quick answer..CHEEEEEEEERS

 CFD_MAN November 27, 2002 20:16

Re: Saffman Lift Force: confused

Have you heard of SLF ? :) Just curious. FLUENT calculates this force.

CFD

 Amid Naz November 28, 2002 06:22

Re: Saffman Lift Force: confused

I know lift due to shear or the viscous lift force..This definetly can be calculated by Fluent.. but you must select viscous slover not inviscid..Good luck..

 mmmahdavimanesh September 9, 2010 04:51

saffman lift force estimation

Dear freinds

I write this termin my code. how should I calculate dij (rate of deformation)?
Assume that particle is within one cell. Is it neccessary to calculate these term in the both side of particle or just derivate and evaluate it in the base of cell?

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