# twoPhaseEulerFoam: turbulence on produces instability of drag phase

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January 19, 2010, 12:45
twoPhaseEulerFoam: turbulence on produces instability of drag phase
#1
Senior Member

Florian Krause
Join Date: Mar 2009
Location: Munich
Posts: 103
Rep Power: 9
Hello,

I am trying to simulate a turbulent air - solid particle two-phase flow in a vertical pipe using twoPhaseEulerFoam. I added a source term (as in channelFoam) in the Ub (continous phase) equation to sustain the flow for the use of cyclic BC's. Further I use wedge BC's.

When I switch turbulence off, everything works fine, meaning I get reasonable axial velocity profiles for Ua and Ub.

From the above state I switch turbulence on, and the velocity of the drag phase Ua starts developing in a wrong "unsteady shape", see the attached picture.

setup:

- OF-1.6.x
- fvSolution and fvScheme are taken from the bed tutorial
- ppForces and kinetic theory is switched off
- drag model: SchillerNaumann
- k is calculated using k = 3/2 (I*U)^2
- epsilon is calculated using epsilon = (c_mu^0.75*k^1.5) / l
- The continous phase bulk Re number is 2.3E+4

I am wondering why the drag phase behaves in such a strange way, after switching on the turbulence model....

Do you have any suggestions, what might be the reason for this behaviour? Or did anyone oberserved similar problems?

Florian
Attached Images
 axial_velocity_profile.jpg (24.6 KB, 39 views) grid.jpg (22.6 KB, 33 views)

 October 11, 2013, 09:02 Same problem #2 New Member   Pedro Lopes Join Date: Jun 2012 Location: Coimbra, Portugal Posts: 4 Rep Power: 6 Hi Florian, I've tried to do the same study, i.e. an bubble column, and happened the same problem as you report. Did you found an solution for your problem with the k-e model? Regards, Pedro

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