CFD Online Logo CFD Online URL
Home > Forums > OpenFOAM Running, Solving & CFD

phase names in multiphaseEulerFoam: strange behaviour

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

LinkBack Thread Tools Display Modes
Old   May 11, 2015, 18:35
Default phase names in multiphaseEulerFoam: strange behaviour
New Member
Pietro Danilo Tomaselli
Join Date: Oct 2012
Location: Lyngby, DTU
Posts: 9
Rep Power: 7
kobelak is on a distinguished road
Hi All,

I have been using multiphaseEulerFoam (OF 2.3.1) to study the evolution of the bubble size distribution in a bubble column. I recently found out that the solver may be surprisingly sensitive to the names given to phases.

I am working on a bubble column case where I defined a water phase and n=7 air phases. The air phases have the same characteristics (rho,nu,...) but different diameters and different names then. I named them as "air01", "air02", "air03",....."air07" with increasing diameter.
I ran my simulation. Phase "air05" showed weird values of velocity, two or three times higher then those ones of the other phases: a sort of "outlier" behaviour. After some struggling, I ran the simulation with the SAME set-up, just changing the name "air05" in "airWhatever": the values of velocity of "airWhatever" were normal!

To investigate the reason, I looked at the log files of the two simulations. I noticed that some differences already arose when the drag models for the phases were selected ("Selecting dragModel for phase...."): I used in both simulations a type "blended" for each (air0X water) interface, but the drag model for the different phases were called in a different order.
Therefore I changed the code in order to output the variable "dragCoeffi" (defined in pEqn.H) which stores the drag coefficients for a given phase.
Running again the two simulations, I realized that the solver calculated the same drag coefficients, but they were differently associated to the phases . In particular, in the simulation with "airWhatever" phase, the order was correct, while in the other simulation, the coefficient of phase "air01" was assigned to "air05" and viceversa. Then I could assume that this was the reason of the wrong velocites of "air05" in the first simulation.

To confirm the speculation, I also ran the damBreak4phase tutorial. I changed the name "mercury" in "smercury". Again, the drag Models were called in a different order and the log files presented slightly different values of time steps, Courant number...even though I would have expected the simulations being identical.

The questions are then the following: where am I wrong? Has anyone experienced anything similar? Is it a sort of bug?

Looking forward for some help. Thanks in advance.

kobelak is offline   Reply With Quote


Thread Tools
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 On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
rhoSimpleFoam - strange behaviour of the residuals Werne OpenFOAM Running, Solving & CFD 2 December 16, 2014 05:27
Strange behaviour: Ethanol solution flow on channel with interface to porous domain khariel CFX 6 December 11, 2014 18:08
Strange residuals behaviour xxxx Main CFD Forum 1 July 13, 2013 14:40
Strange behaviour when using LienCubicKE and NonlinearKEShih hani OpenFOAM Running, Solving & CFD 20 March 6, 2013 11:06
compressible two phase flow in CFX4.4 youngan CFX 0 July 1, 2003 23:32

All times are GMT -4. The time now is 15:29.