tank sloshing overflow error

enghamed · January 19, 2011, 23:34

I have modeled a recetangular tank with a unit thickness (2D) and runs well but when I change the mesh to cylinder tank (3D) with all the same conditions for the 2D, I get fatal overflow error!!!
why is this happening? what should I do?

ghorrocks · January 20, 2011, 04:19

Can you describe what you are doing a bit better?

But the problem is probably mesh quality.

enghamed · January 20, 2011, 20:38

I want to model water sloshing in a cylinder tank.
As a first attempt I modeled a rectangular tank with two faces of symetry and the top as open and the other three faces as wall. Defined the mesh displacment for the wall as x=Asinwt. It ran very good.
Now i change the goemetry with a cylindrecal tank and didn't change any settings, but now i get error of "Floating point exception: Overflow".
I have meshed the goemetry in ICEM with an o-grid.
any more details you need?

enghamed · January 21, 2011, 00:37

I now tried a 3D rectangular and agian got the overflow error.
It shouldn't be the quality of the mesh since now I have a complete square hex elements!
Have u got any idea what is going wrong?

regards

ghorrocks · January 21, 2011, 06:28

No idea what is wrong.

Add the physics into the model one step at a time. Does the 3D model work with a static mesh, but the initial free surface deformed somehow to start a motion? Does the model work with a motion of a small magnitude?

zcesd47 · June 24, 2011, 13:55

hi,enghamed
I am now modeling a case very similar to your one, the water sloshing in a rectangular tank, I use two domains one as water and the other as air, and applied the displacement sin(wt) to the walls of the tanks. initial condition for air domain volume fraction air= 1& volume fraction water =0. The contrast for water domain. But when I try to solve it, the solver terminate at the 1st timestep, the linear solution for U-mom V-mom and P-vol failed. I change my B.C and timesteps but doesn't help. Do you have any suggestions for my problem. Could you tell me how you set you interface and initial conditions. Very much appreciated.

Regards

Dijun

ghorrocks · June 25, 2011, 06:50

Do the tutorial free surface flow over a bump for ideas of how to set up and run free surface models.

zcesd47 · June 25, 2011, 13:19

Thank you . It seems that I define the Buoyancy ref. density as Water's density instead of air's.

January 19, 2011, 23:34	tank sloshing overflow error	#1
enghamed Member Hamed Join Date: Jun 2010 Posts: 43 Rep Power: 16	I have modeled a recetangular tank with a unit thickness (2D) and runs well but when I change the mesh to cylinder tank (3D) with all the same conditions for the 2D, I get fatal overflow error!!! why is this happening? what should I do?

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January 20, 2011, 04:19		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,934 Rep Power: 145	Can you describe what you are doing a bit better? But the problem is probably mesh quality.

January 20, 2011, 20:38		#3
enghamed Member Hamed Join Date: Jun 2010 Posts: 43 Rep Power: 16	I want to model water sloshing in a cylinder tank. As a first attempt I modeled a rectangular tank with two faces of symetry and the top as open and the other three faces as wall. Defined the mesh displacment for the wall as x=Asinwt. It ran very good. Now i change the goemetry with a cylindrecal tank and didn't change any settings, but now i get error of "Floating point exception: Overflow". I have meshed the goemetry in ICEM with an o-grid. any more details you need?

January 21, 2011, 00:37		#4
enghamed Member Hamed Join Date: Jun 2010 Posts: 43 Rep Power: 16	I now tried a 3D rectangular and agian got the overflow error. It shouldn't be the quality of the mesh since now I have a complete square hex elements! Have u got any idea what is going wrong? regards

January 21, 2011, 06:28		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,934 Rep Power: 145	No idea what is wrong. Add the physics into the model one step at a time. Does the 3D model work with a static mesh, but the initial free surface deformed somehow to start a motion? Does the model work with a motion of a small magnitude?

June 24, 2011, 13:55		#6
zcesd47 New Member Dijun Pan Join Date: Jun 2011 Posts: 13 Rep Power: 15	hi,enghamed I am now modeling a case very similar to your one, the water sloshing in a rectangular tank, I use two domains one as water and the other as air, and applied the displacement sin(wt) to the walls of the tanks. initial condition for air domain volume fraction air= 1& volume fraction water =0. The contrast for water domain. But when I try to solve it, the solver terminate at the 1st timestep, the linear solution for U-mom V-mom and P-vol failed. I change my B.C and timesteps but doesn't help. Do you have any suggestions for my problem. Could you tell me how you set you interface and initial conditions. Very much appreciated. Regards Dijun

June 25, 2011, 06:50		#7
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,934 Rep Power: 145	Do the tutorial free surface flow over a bump for ideas of how to set up and run free surface models.

June 25, 2011, 13:19		#8
zcesd47 New Member Dijun Pan Join Date: Jun 2011 Posts: 13 Rep Power: 15	Thank you . It seems that I define the Buoyancy ref. density as Water's density instead of air's.