# A Physical Anomaly in tutorials/interFoam/laminar/damBreak

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

March 22, 2014, 00:13
A Physical Anomaly in tutorials/interFoam/laminar/damBreak
#1
Member

xuhe-openfoam
Join Date: Aug 2013
Location: DaLian，china
Posts: 82
Rep Power: 4
Hello , everyone !
I found a Physical Anomaly in tutorials/interFoam/laminar/damBreak case !

I didn't modification any other thing except for the regions in setFieldsDict ! That is :

regions
(
boxToCell
{
box (0 0 -1) (1.1461 0.292 1);
fieldValues
(
volScalarFieldValue alpha1 1
);

This just fill up the tank about halfway with water. Then began to compute.
Certenly, it is in a condition of rest ! So the Pressure and Velocity should be arround zero .
But I found the wave amplitude of Pressure and Velocity is bigger and bigger in the course of time! Though the amplitude of Pressure and Velocity is still very small, it becomes bigger when there is no energy input !
I think it is a wrong numerical result!

could you help me ? How to solve this problem!
thanks!
Attached Images
 01.jpg (79.3 KB, 12 views)

 March 22, 2014, 01:19 #2 Senior Member   Cyprien Join Date: Feb 2010 Location: Stanford University Posts: 230 Rep Power: 9 Hi, this problem is very probably due to spurious currents which are intrisinsic to the VoF formulation as implemented in OF. Some scientists have proposed more or less efficient solutions to remove this indesirable phenomenon, but they have never been included in the official release. They are several threads on the forum (look for "parasistic currents"). Best, Cyp

 March 22, 2014, 01:38 #3 Member   xuhe-openfoam Join Date: Aug 2013 Location: DaLian，china Posts: 82 Rep Power: 4 thank you! I wish the opencfd could improve it! because the spurious currents will lead to divergency in fluid and strcucture interaction numerical computation, especially when the elasticity modulus of the structure is a little small. If the problem couldn't be solved , I have to give up the twophase fluid !

March 22, 2014, 04:33
#4
Super Moderator

Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 8,511
Blog Entries: 34
Rep Power: 86
Quote:
 Originally Posted by bieshuxuhe thank you! I wish the opencfd could improve it! because the spurious currents will lead to divergency in fluid and strcucture interaction numerical computation, especially when the elasticity modulus of the structure is a little small. If the problem couldn't be solved , I have to give up the twophase fluid !
Quick answer: Don't blame the software, if you don't understand the physics in play by the solver due to the mesh and boundary conditions .
Because this exact experimentation has already been explained here: dambreak tutorial's weird velocity field. - it's a long read, but it should clear up any misconceptions of "it should just work, because it worked in a commercial software".

You might also want to check this blog post of mine: OpenFOAM: Interesting cases of bad meshes and bad initial conditions

 March 22, 2014, 05:00 #5 Member   xuhe-openfoam Join Date: Aug 2013 Location: DaLian，china Posts: 82 Rep Power: 4 Thanks for your help !

 Tags nonconservation of energy

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post msrinath80 OpenFOAM Running, Solving & CFD 18 March 3, 2015 06:36 immortality Lounge 1 December 8, 2013 16:04 aeroslacker Open Source Meshers: Gmsh, Netgen, CGNS, ... 12 January 19, 2012 04:52 7islands Open Source Meshers: Gmsh, Netgen, CGNS, ... 35 April 1, 2010 05:13 msrinath80 OpenFOAM Running, Solving & CFD 1 November 11, 2007 00:23

All times are GMT -4. The time now is 15:16.