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Falling ball
Posted 7 nov 2012, 11:16 GMT-5 2 Replies
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Hi,
I am trying to simulate a falling ball inside a fluid, this is for simulate a falling ball viscometer. I'm working in transient mode, with the sphere like "sliding wall" and the tube like "no slip", when I make the simulation with bigger dimensions it kind of works, but when i do it with the real dimensions, the simulation does not work.
I am not sure what is missing, I should take into account the gravity? If so, how should I do it?
The model is a tube with a sphere in the bottom, when I play the animation the fluid beggins to change near the sphere, but it doesn't reach all the fluid (the sphere never moves), I don't know how to simulate the falling ball in the fluid. How should I do it?
Thank you very much
I am trying to simulate a falling ball inside a fluid, this is for simulate a falling ball viscometer. I'm working in transient mode, with the sphere like "sliding wall" and the tube like "no slip", when I make the simulation with bigger dimensions it kind of works, but when i do it with the real dimensions, the simulation does not work.
I am not sure what is missing, I should take into account the gravity? If so, how should I do it?
The model is a tube with a sphere in the bottom, when I play the animation the fluid beggins to change near the sphere, but it doesn't reach all the fluid (the sphere never moves), I don't know how to simulate the falling ball in the fluid. How should I do it?
Thank you very much
2 Replies Last Post 7 nov 2012, 14:20 GMT-5
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Posted:
1 decade ago
Hi
whicj are the forces acting on the sphere, normally it's gravity who "pulls" it down, and boyance vorce that makes it lift, not to say fluid flow to sloww it down.
So I would say yes you need gravity, on the sphere and on the fluid (at least to be "physically correct, perhaps not to start with if you feel it adds up to many variables at one time).
Then as the ball falls, it will deform the mesh, for that you need ALE, or get it all "cooked up" by the combined physics FSI module
--
Good luck
Ivar
whicj are the forces acting on the sphere, normally it's gravity who "pulls" it down, and boyance vorce that makes it lift, not to say fluid flow to sloww it down.
So I would say yes you need gravity, on the sphere and on the fluid (at least to be "physically correct, perhaps not to start with if you feel it adds up to many variables at one time).
Then as the ball falls, it will deform the mesh, for that you need ALE, or get it all "cooked up" by the combined physics FSI module
--
Good luck
Ivar
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Posted:
1 decade ago
Best way as is to use the FSI module as Ivar described. However, you can get a good solution with a CFD model only by providing a “Slip velocity” boundary condition (an option under the Wall boundary condition) on the surface of the ball. You should then adjust the slip velocity until the ball is in equilibrium, meaning that is the drag force equals the gravity/buoyancy force.
Nagi Elabbasi
Veryst Engineering
Nagi Elabbasi
Veryst Engineering