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xfish November 4, 2003 21:01

problem about modelling fluidized bed!
hi , i am simulating flow field of the fluidized bed.can anyone tell me that which viscous model should be available in the case of CFB! So grate for your help!

ap November 5, 2003 12:03

Re: problem about modelling fluidized bed!
Fluent 6.0 and 6.1 allow you can do laminar calculations and turbulent ones using k-eps models (Standard, RNG, Realizable).

Also, you can calculate the granular phase viscosity using Gidaspow or Syamlal correlation for the kinetic contribution, which are based on the kinetic theory.

Schaeffer's correlation for frictional viscosity can be used too.

Hi :)


xfish November 5, 2003 23:21

Re: problem about modelling fluidized bed!
ap,thanks for you comment! But i means should i use turbulent model or laminar model in simulating circulate fluidized bed(CFB)?i know laminar model is available in bubbling fluidized bed!

ap November 6, 2003 09:42

Re: problem about modelling fluidized bed!
I'd suggest to activate turbulence, in order to better describe the behaviour of the flow.

What are operating conditions (Ug, Gs, reactor diameter and particle density) of the reactor?

You can find many articles in literature where it is demonstrated the influence of turbulence in modeling CFB reactors.

Many authors used a LES approach to describe the turbulence of gas phase. Others developed a modified k-eps model (k-eps-k_p-eps_p) both for gas and solid phases, which gives interesting results.

Both these models are not available in FLUENT: LES can't be used in multiphase calculations, and the k-eps model differs from the k-eps-k_p-eps_p.

Moreover, keep in mind that FLUENT uses an algebraic formulation of the granular temperature balance and not the full differential equation.

Hi :)


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