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Old   December 13, 2017, 06:59
Default tangential vector tolerance wall
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Davide
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Anyone knows how to change the expert parameter "tangential vector tolerance wall" in CFX? Because I see only the parameter tangential vector tolerance without "WALL"..
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Old   December 14, 2017, 09:16
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I must solve the fluidynamic inside a tire of a car to study the behaviour of the braking system. So in a steady state in CFX I set that some components have a rotating velocity. Due to the complexity of the geometry I have made an unstructured mesh, but when I starts the run CFX tells me that the angle between the specified velocity and the element surface is higher, so it suggests to increase the tolerance in the expert parameter "tangential vector tolerance wall" from its default of 20 degrees. The problem is that this expert parameter there isn't. Someone knows how to find this expert parameter that probabilly exist but is hidden???
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Old   December 14, 2017, 19:55
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Are you sure you are not prescribing a normal velocity somewhere? The default of 20 degrees is plenty for most applications so if you infringe this it probably means something is wrong with your mesh or geometry - increasing the tolerance is rarely the appropriate response.
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Old   December 15, 2017, 09:33
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No my domain is a cubic box in which there is the tire with the braking system in the interior. In a face of the cubic domain I set the velocity inlet condition, while in the tire I set a wall no slip condition with a wall rotating velocity. Do you know how to find the above expert parameter, because I would try to solve my problem without changing the mesh.. Therefore my problem is that the expert parameter "tangential vector tolerance wall" in reality I cannot find in CFX... Can you help me to find this expert parameter?
Thanks
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Old   December 15, 2017, 09:34
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Quote:
Originally Posted by ghorrocks View Post
Are you sure you are not prescribing a normal velocity somewhere? The default of 20 degrees is plenty for most applications so if you infringe this it probably means something is wrong with your mesh or geometry - increasing the tolerance is rarely the appropriate response.
No my domain is a cubic box in which there is the tire with the braking system in the interior. In a face of the cubic domain I set the velocity inlet condition, while in the tire I set a wall no slip condition with a wall rotating velocity. Do you know how to find the above expert parameter, because I would try to solve my problem without changing the mesh.. Therefore my problem is that the expert parameter "tangential vector tolerance wall" in reality I cannot find in CFX... Can you help me to find this expert parameter?
Thanks
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Old   December 15, 2017, 18:55
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I am not on my workstation today so cannot look this up for you. But please note my previous post - this is probably caused by a meshing error which should be fixed by fixing the meshing error, not by allowing a larger tolerance.
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Old   December 18, 2017, 09:53
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Quote:
Originally Posted by ghorrocks View Post
I am not on my workstation today so cannot look this up for you. But please note my previous post - this is probably caused by a meshing error which should be fixed by fixing the meshing error, not by allowing a larger tolerance.
ok thanks, when you are on your workstation can you look if you find this expert parameter?
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Old   December 18, 2017, 10:48
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I agree with Glenn, this is probably a mesh issue.
But anyway, some expert parameters are hidden in the gui so if you really want to change the it the following trick might work:
open expert parameters, check "tangential vector tolerance", hit apply, close tab.
right click expert parameters in the tree, edit in command editor.
enter: tangential vector tolerance wall = 20.0

note: I havent tried it, it might not work, and you really should see if you can improve your mesh instead.
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Old   December 18, 2017, 11:42
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Quote:
Originally Posted by Lance View Post
I agree with Glenn, this is probably a mesh issue.
But anyway, some expert parameters are hidden in the gui so if you really want to change the it the following trick might work:
open expert parameters, check "tangential vector tolerance", hit apply, close tab.
right click expert parameters in the tree, edit in command editor.
enter: tangential vector tolerance wall = 20.0

note: I havent tried it, it might not work, and you really should see if you can improve your mesh instead.
thank you so much I do not know how to thank you ... it was enough to follow your procedure to activate the hidden expert parameter
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