surface monitors in VOF

prashanthreddyh · September 28, 2010, 20:10

I am modeling free surface flow in an open channel using FLUENT software. I have defined a surface monitor for the massflow on top boundary which is subjected to atmospheric pressure. After few thousand iterations, results (residual monitor) shows mass inbalance between inflow and outflow. The surface monitor (on top) shows 4% of the fluid is escaping from the top boundary. What does it mean? please explain me whether it is normal that fluid escapes from free surface boundary. How to correct it if it is not correct.

Thanks in advance

pranab_jha · September 29, 2010, 11:53

Well, that could related to computational issues. Your mesh might not be sufficiently fine to compute and give you a converged solution. I would try making a finer mesh, as well as using a smaller time step. Also, you can try using some other discretization method and compare your results.

prashanthreddyh · September 29, 2010, 12:07

Hi Jha,

Thank you so much.

Prashanth

September 28, 2010, 20:10	surface monitors in VOF	#1
prashanthreddyh New Member Prashanth Join Date: Nov 2009 Posts: 6 Rep Power: 16	I am modeling free surface flow in an open channel using FLUENT software. I have defined a surface monitor for the massflow on top boundary which is subjected to atmospheric pressure. After few thousand iterations, results (residual monitor) shows mass inbalance between inflow and outflow. The surface monitor (on top) shows 4% of the fluid is escaping from the top boundary. What does it mean? please explain me whether it is normal that fluid escapes from free surface boundary. How to correct it if it is not correct. Thanks in advance

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September 29, 2010, 11:53		#2
pranab_jha Member Pranab N Jha Join Date: Nov 2009 Location: Houston, TX Posts: 86 Rep Power: 16	Well, that could related to computational issues. Your mesh might not be sufficiently fine to compute and give you a converged solution. I would try making a finer mesh, as well as using a smaller time step. Also, you can try using some other discretization method and compare your results.

September 29, 2010, 12:07		#3
prashanthreddyh New Member Prashanth Join Date: Nov 2009 Posts: 6 Rep Power: 16	Hi Jha, Thank you so much. Prashanth