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How to specify a tangential velocity for a moving wall? |
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July 14, 2022, 15:16 |
How to specify a tangential velocity for a moving wall?
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#1 |
New Member
De Broglie
Join Date: Jul 2022
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The title pretty much says it. Imagine we have a physically moving wall, for which the motion is prescribed using pointDisplacement as boundary condition. But we need to also specify an additional tangential wall velocity for which no mesh movement is necessary. How do we go about this?
Thanks a bunch in advance for any help. |
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July 14, 2022, 15:33 |
rotatingWallVelocity
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#2 |
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Al Csc
Join Date: Jul 2018
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For ESI-v2206, you find the answer in:
- If rotating, ie cylinder: OpenFOAM-v2206/src/finiteVolume/fields/fvPatchFields/derived/rotatingWallVelocity/rotatingWallVelocityFvPatchVectorField.H Code:
Description This boundary condition provides a rotational velocity condition. Usage \table Property | Description | Required | Default value origin | origin of rotation in Cartesian coordinates | yes| axis | axis of rotation | yes | omega | angular velocty of the frame [rad/s] | yes | \endtable Example of the boundary condition specification: \verbatim // Here what you need: <patchName> // for U { type rotatingWallVelocity; origin (0 0 0); axis (0 0 1); omega 100; } Code:
Description This boundary condition provides a velocity condition for cases with moving walls. Usage Example of the boundary condition specification: \verbatim //What you need: <patchName> // for U { type movingWallVelocity; value uniform (0 0 0); // Initial value } \endverbatim Last edited by al.csc; July 14, 2022 at 15:39. Reason: missing second part |
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July 14, 2022, 15:38 |
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#3 |
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De Broglie
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Thank you, al.csc, for replying. But I believe this is a BC that should not be used when the wall is physically moving. Say you have a cylinder that is rotating around its center, then you wouldn't need a mesh movement and could use rotatingWallVelocity safely.
My question relates to when the wall is actually moving. Think a linearly oscillating cylinder that is also rotating at the same time. The oscillation needs mesh movement, whereas the rotation doesn't. |
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July 14, 2022, 15:43 |
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#4 | |
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Al Csc
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Quote:
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July 14, 2022, 15:45 |
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#5 |
New Member
De Broglie
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Ok, on movingWallVelocity, this BC works well (and should be used) when the wall is physically moving. The problem is that sometimes you don't want the wall to have an actually movement in the tangential direction. In such situations if movingWallVelocity is used, the mesh actually moves in the tangential direction, which is not desirable.
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July 14, 2022, 15:50 |
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#6 | |
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De Broglie
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Quote:
No worries, at all. Sometimes you would want to prescribe a specific velocity on the wall in tangential direction, which simulates a wall movement (without the actual movement and hence no need for mesh motion). |
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July 14, 2022, 15:55 |
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#7 |
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De Broglie
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Just to add to this, in commercial codes like Fluent or CFX, and when you have dynamic mesh, you could specify a "relative wall velocity" on wall boundaries in addition to wall mesh motion, which would take care of this problem.
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October 26, 2024, 13:21 |
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#8 |
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Lupo Ci
Join Date: Aug 2010
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De_Broglie where you able to solve this problem? And how? Is it possible to prescribe a moving boundary wall that does not move the mesh? I need to move my wall tangentially to the wall itself, not perpendicularly. Does it carry the mesh with it this way?
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Tags |
dynamic mesh, moving wall, tangential velocity |
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