Multiphase Eulerian Gas-Solid Flow
I try to simulate gas-solid flow (w/o any reaction) in a 7m-riser with Fluent 6.3 - Eulerian multiphase model (with single solid phase). Air is fed from bottom and solids as side inlets above 0.5 m gas inlet. I have quite a dilute flow (10kg/m2s). Main points of my model:
Solver: unsteady (transient) â€" 2D
Solution Controls: URFs = Defaults
Discretization = First-Order Upwind
Granular Temperature Model: Partial Differential Equation
Gas-Solid Drag : Gidaspow
Viscous model: k-epsilon
k-Epsilon model: Realizable / dispersed
Near-wall treatment: standard wall functions
(No UDFs used for turbulent viscosities)
My current mesh with boundary layer is fine enough. 50 elements in radial direction.
Time step: 1*10**(-4) max. iter. 30 (slowly increased to this and kept constant)
My problem is simulation goes quite well and converges at every time step in the beginning. And particles rise within the riser. After 1-1.5 sec, particles start to get collected near the walls (below 2 m of outlet line). And when it gets dense enough (like a layer/dead zone with a thickness of 20-30 cm), particles suddenly collapse and leave riser from bottom/gas inlet. And I am 100% sure that I am well above choking regime.
Unfortunately I couldn't find a solution for this. Does anyone has a similar experience? And any idea how to solve this case?
Thanks in advance,
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