CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT > Fluent Multiphase

Gas-solid modeling (Fluidized Bed)

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Search this Thread Display Modes
Old   August 29, 2013, 06:40
Default Gas-solid modeling (Fluidized Bed)
New Member
Join Date: Apr 2010
Posts: 2
Rep Power: 0 is on a distinguished road
Dear all,

I'm working on simulation of gas-solid contact process, starting from a Bubbling Fluidized Bed (BFB) to a Fast Fluidized Bed (FFB).
But I have a problem with loss of mass within my system, while I'm assured that there is no mass flow rate out of my system from outlets.

For example, a bed which is fluidized around its minimum fluidization velocity (U_mf). Mass of solid disappears around 90% after 2-3 seconds of flow time. This rate would be lower while I increase the fluidization velocity.

Example: Considering a 2D problem,
- bed (W=0.3, H=0.5)m
- solid particles (ro=3000 kg/m3) (d_p=200e-6 m)
- Gas phase (air)

V_mf~=0.05 m/s
U_terminal~=1.5 m/s
V_gas=0, 0.1 m/s, 0.5 m/s and so on

Eulerian-Eulerian Model
(Both laminar and turbulent methods were tested)
Solid phase, granular fluid: Granular viscosity-> Gidaspow; Granular Bulk Viscosity-> Luen et al; Interaction of phases-> Symlal-Obrien

if I filled in the bed e.g. 50% with solids... and run the fluent in transient mode (which the time step is dt<dx*dy) dx&dy=0.01m

*** The mass of solid in the bed, start decreasing after a while and approaching zero while the flow time increases.

So, the question is "what is the source of this degradation in mass of solids"
could it be generated due to wrong model, or the mesh size and time step should be more fine?!

Additionally, I followed a simulated problem in an article which the writers compared the results with experiments (mesh size and time step were implied by that paper)... I also have missing in solid mass!!!

Thanks in advance for reading my long comment is offline   Reply With Quote


fludized bed, loss of mass, multiphase flow

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
gas solid flow in circulating fluidized bed with different gas velocity kongl1986 FLUENT 2 April 5, 2012 22:23
error message cuteapathy CFX 14 March 20, 2012 06:45
Converge problem for unsteady gas solid flow kongl1986 FLUENT 5 March 1, 2012 16:31
create solid viscosity UDF in fluidized bed hosseini FLUENT 1 June 22, 2007 12:19
Gas pressure question Dan Moskal Main CFD Forum 0 October 24, 2002 22:02

All times are GMT -4. The time now is 01:58.