mass conservation problem with VOF model

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

 LinkBack Thread Tools Display Modes
 August 10, 2008, 14:57 mass conservation problem with VOF model #1 pat77 Guest   Posts: n/a Hello, Well, I have a problem... I am working on a two-phase flow simulation in a long pipe. I am using the VOF model(steady). The boundary conditions I use are the following: 1) velocity inlet for phase 1 2) velocity inlet for phase 2 3) outflow The simulation seems OK and converged. However, I don't get mass conservation even when I decrease the residual. Is there something wrong with my simulation or is it something to do with the VOF model? Here is what I obtain: mixture Mass Flow Rate (kg/s) inlet_inf 45.185421 inlet_sup 217.28444 outlet -222.14208 Net 40.327781 Any idea would be great. Many thanks! pat77

 October 31, 2012, 03:37 #2 New Member   Join Date: Oct 2012 Posts: 6 Rep Power: 4 Hi, I have the same problem. I'm simulating the two-phase air-water flow in a corrugated pipe of 60 m long but it turns out to be a significant mass imbalance between inlet and outlet. May the problem be due to curvature of corrugations? Corrugations are annular and quite frequent with a depth to pitch ratio of 1/5. (Depth is height of corrugation, while pitch is distance between each corrugation element). I haven't had any problem with smaller ratios using the same model. I modeled only the quarter pipe, assigning symmetry condition to the longitudinal mid-plane of the pipe. The top boundary is defined as wall, except for a small face on it near the pipe inlet, to allow air in where velocity inlet BC is applied. Pipe inlet is defined as mass flow inlet for water. The discretizaton scheme i employed for volume fraction is Modified HRIC. Any help would be appreciated. Regards, Kenan

 November 5, 2012, 08:07 #3 New Member   Join Date: Oct 2012 Posts: 6 Rep Power: 4 I got the solution. I found out that it was just because of coarseness level of the grid, as the VOF method needs finer grid to resolve the flow structures in curvature-dominated flows. So i created a finer mesh especially in the region where free surface to be formed. Then mass gain / loss has dissappeared.

 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 Prabhas FLUENT 0 December 5, 2006 02:15 Jaswant Main CFD Forum 8 July 4, 2005 22:32 Balaji FLUENT 0 May 11, 2005 07:16 Diego Nogueira Main CFD Forum 1 July 30, 2004 15:50 philippe FLUENT 8 May 5, 2003 11:43

All times are GMT -4. The time now is 15:37.

 Contact Us - CFD Online - Top