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Juliana P September 19, 2005 07:50

Help needed to model gas-solids flow
Dear all,

me need help! Am trying to model a hopper flow. Am completely new to Fluent. The tutorials have that of an impeller liquid-gas but not solids-gas. After much reading up, I am still abit now where.

Which turbulent model should I use? It is not mixture as the density of the secondary phase (i.e. solids materials) are much higher than the primary phase (air). It is not dispersed turbulence as the secondary phase is not dilute. (or is it? what is consider dilute? The solids are loaded into a hopper and made to flow out). Can i model it as laminar flow?

Also the boundary condition at the outlet? Should I use outflow or pressure outlet? Things like velocity at outlet I do not know. I thought should be calculated by FLUENT?

Please help if anyone can.Thanks a lot everyone.

Juliana P

Podila September 19, 2005 15:44

Re: Help needed to model gas-solids flow
Dispersed Multiphase K-e model as it treats turbulence in each phase separately. Pressure outlet.. Read paper by Davor Cockljat. It will help you to understand why dispersed k-e model has to be used.

laminar or Turbulent???? Calculate Nre for continuous phase.

Juliana P September 19, 2005 23:08

Re: Help needed to model gas-solids flow
Hi Podila and others who can help,

I tried to search for Davor Cockljiat. It produced the following : High performance computing for river engineering. Proceedings of the 1996 Parallel Computational Fluid Dynamics Conference, CFD, 1997, p 84. But I don't have access to it. Can you kindly send me at

if you have the paper. Will this paper help me loads? How do I determine the boundary conditions, is it through trial and error or are there papers to read? Really thanks for your help.

Also I want to ask what is Nre? you mean reynolds it? How to calculate if I do not know velocity? Re= (density x velocity x characteristic length) / (kinematic viscosity) right? Many thanks again.

thanks Juliana P

Podila September 21, 2005 09:42

Re: Help needed to model gas-solids flow
Cockljat, D. and V. A. Ivanov, F. J. Sarasola, S. A. Vasquez, "Multiphase k- models for Unstructured Meshes" ASME 2000 Fluids Engineering Division Summer Meeting, Boston, 2000.

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