Reversed flow in vof model or water damping

David712 · October 9, 2018, 21:53

I am trying to simulate an example for a flow around a circle based on a stratified circumstance which also contain the air in a planar. If I use a pressure outlet for the 'out', there are reversed flow finding in the outlet even I had tried to use an udf for the pressure.
Whats more, if I use an outflow for the 'out', no reversed flow would be found but the water near the 'out' seems to rise or damp maybe.
I want to know there is a way to avoid such kinds of 'mistakes' because no matter which kind of 'mistake' do effect the flow field of the simulation.

RaiderDoctor · October 9, 2018, 21:56

How close is your outlet to the cylinder? Can you post some pictures of the setup and solution (preferably with a contour map and velocity vectors shown). Finally, what does your mesh look like?

David712 · October 9, 2018, 22:29

http://a4.qpic.cn/psb?/a2e89427-7d40...=photolist&t=5
http://a1.qpic.cn/psb?/a2e89427-7d40...=photolist&t=5
http://a4.qpic.cn/psb?/a2e89427-7d40...=photolist&t=5
http://a4.qpic.cn/psb?/a2e89427-7d40...=photolist&t=5

The first picture is the wave-height for the surface flow(simulate a short time so the wave damping or rising is not obvious)
Second picture is the flow field of the circle;
Third picture is the mesh condition;
Fourth picture is the phase condition(three phase);

RaiderDoctor · October 9, 2018, 22:35

I can't open any of your photos. Make sure you save them in a good format (.png or .jpeg) and attach them by clicking "Manage Attachments" in the "Additional Options" section on the forum.

October 9, 2018, 21:53	Reversed flow in vof model or water damping	#1
David712 New Member Join Date: Oct 2018 Posts: 17 Rep Power: 7	I am trying to simulate an example for a flow around a circle based on a stratified circumstance which also contain the air in a planar. If I use a pressure outlet for the 'out', there are reversed flow finding in the outlet even I had tried to use an udf for the pressure. Whats more, if I use an outflow for the 'out', no reversed flow would be found but the water near the 'out' seems to rise or damp maybe. I want to know there is a way to avoid such kinds of 'mistakes' because no matter which kind of 'mistake' do effect the flow field of the simulation.

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October 9, 2018, 21:56		#2
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 10	How close is your outlet to the cylinder? Can you post some pictures of the setup and solution (preferably with a contour map and velocity vectors shown). Finally, what does your mesh look like?

October 9, 2018, 22:29		#3
David712 New Member Join Date: Oct 2018 Posts: 17 Rep Power: 7	http://a4.qpic.cn/psb?/a2e89427-7d40...=photolist&t=5 http://a1.qpic.cn/psb?/a2e89427-7d40...=photolist&t=5 http://a4.qpic.cn/psb?/a2e89427-7d40...=photolist&t=5 http://a4.qpic.cn/psb?/a2e89427-7d40...=photolist&t=5 The first picture is the wave-height for the surface flow(simulate a short time so the wave damping or rising is not obvious) Second picture is the flow field of the circle; Third picture is the mesh condition; Fourth picture is the phase condition(three phase);

October 9, 2018, 22:35		#4
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 10	I can't open any of your photos. Make sure you save them in a good format (.png or .jpeg) and attach them by clicking "Manage Attachments" in the "Additional Options" section on the forum.