twoPhaseEulerFoam: turbulence on produces instability of drag phase
 

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.... :confused:

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

Thanks in advance,
Florian

Same problem
 

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