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-   -   2D Tank Sloshing (http://www.cfd-online.com/Forums/cfx/110341-2d-tank-sloshing.html)

rajeshfromindia December 8, 2012 20:38

2D Tank Sloshing
 
Hello everyone,
I have successfully made my tank to slosh by the body force approach. The behviour of the fluid is what I expected. But while reading the impact pressures, I get negative values at all timesteps. I am using no slip walls as the boundary condition for all six sides of the wall. Any thoughts on why I get this porblem. Is my boundary condition right. I would really appreciate if anyone could please help me out.
:)

ghorrocks December 9, 2012 05:46

Have a think about how the reference pressure would work in your implementation. It might just be explained by the static head of the fluid.

Other than that you would have to explain what is being modelled better - an image would help, preferably with labels to tell us what is going on.

rajeshfromindia December 15, 2012 10:57

1 Attachment(s)
Hello Ghorrocks,
Apologies for the late reply. The image attached below is what I have modelled so far. I am trying to investigate the pressure variation on a rectangular tank due to sloshing. The slohing behaviour of water in the tank is as expected. But when I measure the pressures at points P1, P2, P3, I get negative values for all cases at P2 and P3. I am using a K- epsilon turbulence model and my boundary conditions are no slip walls for all six sides of the tank. I tried running a simulation with the top as an opening which gave me better reults with positive values at P2 and P3. Since I will be examining with higher tank fill levels, I cant have open top tank. Could I please have any suggestions regarding the boundary condition I should use in the top wall. Is the boundary conditions wrong or is there any other issue with my model?
Kind Regards,
Rajesh :)

ghorrocks December 16, 2012 05:39

You need something to set the pressure level. Incompressible solvers do not handle closed domains well at all - small numerical errors grow to cause pressure problems and convergence suffers. Best implement whatever gizmo the actual device has to maintain pressure in the model - does it have a small hole to atmosphere? Or a valve or something? If it truly is closed then consider modelling the air as a compressible ideal gas and the pressure will be more under control (but the complexity of the model will increase).

amit kumar baghel December 18, 2012 03:02

Regarding in sloshing problem
 
Hello rajesh,
i am also doing sloshing problem in rectangular tank.I am doing in starccm software.In my case i defined a reference pressure point at center of top wall.if you are using starccm this option is available in solver option.I also defined reference pressure by using user defined function.This option is available reference.In reference got reference pressure there you defined the udf.i defined the udf in this manner

$$Centroid[1]<=0.12 ? 997.56*9.81*(0.12-$$Centroid[1]):0

in my case fluid height was 0.12 m.You keep fluid height according to you problem.
I got the correct result.

rajeshfromindia December 18, 2012 11:36

Thanks a lot Mr. ghorrocks and Mr. Amit Kumar,
I have now set a reference pressure level on the centre of the top wall and I am able to obtain the desired results. I really appreciate your reply.
Thanks once again.
Rajesh :)

mzy012100 February 28, 2013 03:15

could you help me with some example, case files about tank sloshing,yeah it make me feel awkward,but i need your help,best wishes!mzy012100@163.com

jinheng March 23, 2013 08:23

Quote:

Originally Posted by rajeshfromindia (Post 396458)
Hello everyone,
I have successfully made my tank to slosh by the body force approach. The behviour of the fluid is what I expected. But while reading the impact pressures, I get negative values at all timesteps. I am using no slip walls as the boundary condition for all six sides of the wall. Any thoughts on why I get this porblem. Is my boundary condition right. I would really appreciate if anyone could please help me out.
:)

hi ,rajeshfromindia
I am a new foamer to simulate the tank sloshing. I have made my tank to slosh too.But I found that your liquid is better than me . I want to know how did you set your Fields and what is it look like about your VECTOR <U>. Because in my case there is a very big air velocity .
Hope that you can give me some hands.
sammy

amit kumar baghel March 31, 2013 02:43

Regarding sloshing in 3d rectunglar tank
 
2 Attachment(s)
Hi,
i am amit from india.I am doing sloshing in a ractunglar tank.dimension of my tank is 1200mm*600mm200mm.I fitted pressure probe at diffent location.
probe 1 -at (1170,0,100)mm
probe 2-at(1200,30,100)mm
probe 3 -at(1200,150,100)mm


My probelm is that i am running my simulation for 10 second .First i tried with using two prism layer.but this time my initial 4 cylces are loooking but 5th cylce is peaks is very high which i think wrong.what can be possible reason.my first image of p2 using two prism layer.

in second case i am not using any prism layer for p2 case till 4 cylce result are good looking but for 5th cycle tof pressure toally get disturbed which is no matching with paper.my fsecond image is pressure plot of p2 without using any prism layer,
what can be possible reason for it?is there any problem in seting i am using starccm.i am applying force by using
F=-A*omega*omega*(sin(omega*t))

A=0.06 m,omega=3.61 rad/s

Dhruval November 15, 2014 12:06

fluid inside rotating drum
 
1 Attachment(s)
hi everyone.. i need same sloshing tank case but with round cavity means round cylinder or drum which filled 25% of fluid and it rotates.. so can anybody help me with my case?

ghorrocks November 16, 2014 05:08

Yes, we can help you. But if you don't explain the problem there is not much help we can offer.

Dhruval November 16, 2014 10:55

1 Attachment(s)
hi..i am trying to run multiphase/interFoam/laminar/damBreak example with changing geometry rectangle to round cylinder .. i did block mesh with cylinder patches -- works,
but while simulation it gives error.. i am uploading my case , please try once and tell me problem.. thanks .
as i need same dam break example with change geometry..:)

ghorrocks November 16, 2014 17:04

Try the open foam forum. This is the CFX forum.


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