# Sloshing around plunging cylinder problem

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 June 13, 2007, 16:53 Hi everybody, Inspired by t #1 Senior Member   Frank Bos Join Date: Mar 2009 Location: The Netherlands Posts: 340 Rep Power: 11 Hi everybody, Inspired by the nice presentation given by Eric Paterson about waves and multi phase stuff, I tried also a nice example using interFoam, version 1.3. It is my first experience with the interFoam solver, but I succeeded in solving the multiphase flow around a plunging cylinder. The boundary conditions are similar compared to the damBreak tutorial. So, walls left, right and lower, and on top atmosphere. At first, the flow is nicely solved (although the mesh is coarse), which is illustrated in the following movie: http://www.aero.lr.tudelft.nl/~frank...ngCylinder.avi The most interesting observation is that the water level rises, which is rather strange. Has anyone any ideas how this is possible. Did I use improper boundary conditions, or is conservation not preserved when mesh motion is used in combination with interFoam. Why is the mesh motion removed from interFoam in the 1.4 release? Regards, Frank __________________ Frank Bos

 June 13, 2007, 22:01 Might be the BC of alpha at th #2 Senior Member   Xiaofeng Liu Join Date: Mar 2009 Location: State College, PA, USA Posts: 118 Rep Power: 10 Might be the BC of alpha at the moving boundary. __________________ Xiaofeng Liu, Ph.D., P.E., Assistant Professor Department of Civil and Environmental Engineering Penn State University 223B Sackett Building University Park, PA 16802 Web: http://water.engr.psu.edu/liu/

 June 14, 2007, 03:16 What do you mean? gamma? I jus #3 Senior Member   Frank Bos Join Date: Mar 2009 Location: The Netherlands Posts: 340 Rep Power: 11 What do you mean? gamma? I just put gamma on the moving wall to be zeroGradient, like the other walls. pd is also set to zeroGradiet on this moving wall. Furthermore, why is mesh motion removed from interFoam in the 1.4 release? Regards, Frank __________________ Frank Bos

 June 14, 2007, 10:24 I think the increase in water #4 Senior Member   Eugene de Villiers Join Date: Mar 2009 Posts: 725 Rep Power: 14 I think the increase in water level is due to the waves at the zeroGradient boundary. Certainly you see the same kind of thing for a wavetank with a zeroGradient outlet alpha boundary. Again this is speculation, but I think the problem is akin to pressure floating in a domain with no fixed value pressure boundaries or cells.

 June 14, 2007, 10:57 So what could be the correct B #5 Senior Member   Xiaofeng Liu Join Date: Mar 2009 Location: State College, PA, USA Posts: 118 Rep Power: 10 So what could be the correct BC for gamma? __________________ Xiaofeng Liu, Ph.D., P.E., Assistant Professor Department of Civil and Environmental Engineering Penn State University 223B Sackett Building University Park, PA 16802 Web: http://water.engr.psu.edu/liu/

 June 14, 2007, 11:36 I'm not sure. And after some r #6 Senior Member   Eugene de Villiers Join Date: Mar 2009 Posts: 725 Rep Power: 14 I'm not sure. And after some reflection, I don't think the wavetank example is related to Frank's problem. Look at the gamma equation in 1.3: ddt(gamma) + div(phi, gamma) + div(phiIR, gamma) If both the fluxes phi and phiIR are zero on the boundary, then the total ammount of gamma should be preserved irrespective of the gamma boundary conditions. phiIR however is a function of the surface curvature and for the moving mesh case, phi will be non-zero on the cylinder surface. I guess the easiest experiment would be to sum these two fluxes over all boundaries to figure out where the imbalance is coming from, i.e. calculate div(phi, gamma) and div(phiIR,gamma) as a global sum.

 June 14, 2007, 13:47 Frank, I'm glad my stuff mo #7 Senior Member     Eric Paterson Join Date: Mar 2009 Location: Blacksburg, VA Posts: 198 Blog Entries: 1 Rep Power: 11 Frank, I'm glad my stuff motivated you! Concerning your problem, how did you set the top of your domain? I would use the Atmosphere b.c. (which sets the pressure), however, I would also make sure to move it much further away from the oscillating cylinder (maybe 5-10 diameters). I would set all of your side walls to noslip to make a case of a cylinder oscillating in a small tank of initially quiescent fluid. Good luck, and keep us informed.

 August 12, 2007, 13:42 Frank, have you solved the inc #8 New Member   Yingfeng Shen Join Date: Mar 2009 Location: Finland Posts: 8 Rep Power: 10 Frank, have you solved the increasing water level problem? I think I got the similar issue when I was trying to simulate a plane moving down towards a drop of water. The volume of the water is actually increasing even there is no wall contact with it yet. The observed gamma value can be much higher than 1.0. I guess this is related to mesh flux, or it might be that my boundary conditions are wrong somewhere. Here I enclose two pictures from paraFoam. The version used is March foam1.3. I am interested to know your progress in the sloshingCylinder case. Yingfeng

 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 Prabodh FLUENT 1 September 27, 2013 13:27 NARSIM FLUENT 1 July 30, 2011 05:35 shen FLUENT 0 November 6, 2007 08:08 suryakant FLUENT 3 August 11, 2005 13:32 S.R.SAHI Main CFD Forum 1 April 15, 1999 22:28

All times are GMT -4. The time now is 02:59.

 Contact Us - CFD Online - Privacy Statement - Top