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#1 |
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Join Date: Jan 2012
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Hi all,
is there anybody know whether a good cfd method could be used to model behivor of rigid body's motion in fluids driven by gravity? I want to study its terminal velocity under different condition. thank you in advance |
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#2 |
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Glenn Horrocks
Join Date: Mar 2009
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Rather than use a rigid body approach wouldn't it be better to do flow past a stationary object, and when the drag equals the mass you have found the terminal velocity? This will be much easier and faster than modelling it as a falling rigid body.
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#3 | |
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Quote:
Hi, Thank you very much for your reply. You mean I need to do several simulations and get the terminal velocity until the force on the particle equals to the net force of gravity and buoyancy? thank you again for your guidance~~ |
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#4 |
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Glenn Horrocks
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Yes, that is correct.
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#5 |
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hi,
thank you very much for your reply, actually, i want to study the velocity of particle in a vessel full with various fluids, then impose mechanical vibration on the vessel and measure particlel's average terminal velocity. so I wonder is there any directly method can be used to medel this case thank you in advance. |
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#6 |
Super Moderator
Glenn Horrocks
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Can't you vibrate the inlet/outlet and impose the various fluids with the flow over a stationary object model too?
It is MUCH easier to have the object fixed and the fluid flowing over it then to have the fluid fixed and the object falling in it. |
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#7 | |
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Quote:
thank you very much for your guidance, when i imposed the vibration on inlet outlet and wall, the geometry will change because particle is still stationary. and the mesh always deform obviously. also, when vessel is being shaked, the drag force is changing, then how to measure it? regards, |
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#8 |
Super Moderator
Glenn Horrocks
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You can measure the drag force with a monitor point. You can output it every time step and average to get the avergae drag.
You should do everything possible to run this with a stationary mesh. If you can replace your outer wall vibrating (which requires moving mesh) with a time dependant inlet and/or outlet then the simulation will be much easier. But if it cannot be done then you are forced to use moving mesh. |
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#9 | |
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