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

Backflow in eulerian multiphase simulation

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

LinkBack Thread Tools Search this Thread Display Modes
Old   June 26, 2009, 07:50
Question Backflow in eulerian multiphase simulation
New Member
Join Date: Jun 2009
Posts: 1
Rep Power: 0
xeusater is on a distinguished road
Hi everyone;

I am having a problem with an eulerian multiphase simulation. I am fluidizing a granular solid in a column reactor.
The 2D domain is a rectangle with the inlet at the bottom, outlet at the top and two free slip walls in the flanks. The granular phase is modeled basically using syamlal-obrien models for almost every parameter.

Solid particle density is about 1500kg/m3 and the gas is approx 4kg/m3 (heavy). The gas velocity is 0.212m/s at the inlet, which should provide an bubbling bed.

Now what happens is that as soon as I start the calculation, I get a huge backflow from the outlet. That is immediately, first iteration, on all faces of the outlet. Eventually the timestep converges, but the gas velocity field is facing downwards, at something like 400m/s.

Now, I have tried changing the timestep up to very small values (1e-9) , changed every Underrelaxation factor to many possible values, tried initializing the gas velocity field at 0m/s or 0.212m/s. Nothing works.

If there is no solids in the domain, then its Ok. But as soon as there is, even if the volume fraction equation is not solved, the problem starts.

Can you help me in this issue?
Thank you very much in advance
xeusater is offline   Reply With Quote


backflow, eulerian, fluidized beds, granular, outlet

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
backflow in a jet simulation Hao CFX 0 October 3, 2008 02:23
Single phase result file for multiphase simulation Kushagra CFX 2 July 8, 2008 21:14
multiphase simulation... 2D flow through an elbow Tim CFX 10 April 3, 2008 18:13
Mass conservation for eulerian simulation. Lohen FLUENT 1 December 12, 2007 10:42
New to multiphase fluent simulation, any tutorials Camps FLUENT 0 September 9, 2006 11:41

All times are GMT -4. The time now is 20:44.