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August 19, 2011, 15:54 |
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#1 | |
New Member
JT.Q
Join Date: Dec 2009
Posts: 11
Rep Power: 16 |
Quote:
good luck for u Last edited by jiangtao167; August 19, 2011 at 16:17. |
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August 21, 2011, 21:31 |
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#2 | |
New Member
mj
Join Date: Apr 2011
Posts: 24
Rep Power: 15 |
Quote:
I set pressure-inlet as BC for inlet domain. Alought I set fixed water level (freesurface level and bottom level), the level of the water change during simulation. Let me know if you have any suggestion for this error please |
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August 21, 2011, 23:33 |
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#3 |
New Member
JT.Q
Join Date: Dec 2009
Posts: 11
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Initialize and Patch operation play an important part in vof simulation. have you followed the recommendations in users guide manual?
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August 22, 2011, 00:43 |
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#4 |
New Member
mj
Join Date: Apr 2011
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August 22, 2011, 08:54 |
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#5 |
Senior Member
Vieri Abolaffio
Join Date: Jul 2010
Location: Always on the move.
Posts: 308
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Are you shure that the rise of freesurface is not caused by blockage effect ( domain too small)?
I assume your bottom boundary is exactely parallel to the flow direction (no bumps, etc) is it rising everywhere or just at specific locations?) Thetraehral mesh or hexa? Can you post some pictures of the problem? |
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August 22, 2011, 20:27 |
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#6 | |
New Member
mj
Join Date: Apr 2011
Posts: 24
Rep Power: 15 |
Quote:
yes I am sure that it's not because of blockage and the bottom exactly is parallel to flow direction. rising is just in inlet flow. there is reverse flow in some cells at air and water border. I fill the body hole with mesh and run it as channel with current (without body)but there is this reverse flow again. |
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August 22, 2011, 22:49 |
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#7 |
Senior Member
Vieri Abolaffio
Join Date: Jul 2010
Location: Always on the move.
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i'm puzzed, i've never encountered this problem. some reversed flow at the outlet can happen at the aerly stages of simulations, but at the inlet... never heard of.
so to recap: pressure inlet with open channel bc, fixed height (no imposed waves), far enought to do not "feel" the effect of the hull; the mesh at the inlet is made such as the freesurface is not across a very big cell, but lies in a refined region pressure outlet open channel hull=no-slip wall all the rest =symmetry. gravity is turned on and intensity and irection is specified accrodingly explicit vof tranisient simulation with no moving mesh. timestep is adequate to sufficently small cfl initialization and subsequent patching is made accordingly to inlet conditions. how about numerical schemes? it's the only thing not considered... apart form turbulence but don't think this is the problem... how about the convergence? what are your residuals for continuity and momenutm? how many iterations per timestep? |
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August 22, 2011, 23:05 |
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#8 | |
New Member
mj
Join Date: Apr 2011
Posts: 24
Rep Power: 15 |
Quote:
i put 20it/timestep and it converges less tahn 20 it the resual of continuty and momentum are in order of e-4 |
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August 23, 2011, 01:04 |
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#9 |
Senior Member
Vieri Abolaffio
Join Date: Jul 2010
Location: Always on the move.
Posts: 308
Rep Power: 16 |
then, i'm sorry but i don't understand what might be the cause. i hope that somebody else can came up with a solution, or you can ask help to ansys support
if the geometry is not confiential try to upload the case somewhere and i might take a look at it, apart from that i don't really know how to help you. |
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