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What are Padé-type filter and low pass filter in CFD? |
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November 15, 2016, 09:53 |
What are Padé-type filter and low pass filter in CFD?
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#1 |
New Member
carl jung
Join Date: Mar 2016
Posts: 15
Rep Power: 10 |
Hi all,
I was reading a Garmann and Visbal's paper, Dynamics of revolving wings for various aspect(J. Fluid Mech, 2014), but couldn't understand how they worked with the grids. Their case is about a single rotating plate in a Cartesian frame. As the wing rotates, the Cartesian frame rotates together with the wing. I have attached a their figure about it. They said "For all revolving wing simulations presented in this work, the entire mesh is moved in a rigid fashion using the prescribed kinematics." I also have data in a fixed Cartesian frame, so I want to rotate the flow data like they did. But I don't understand most of methods they used such as Padé-type filter, Higher order Low-pass filter. I have no idea how the filters are used numerical calculation in CFD. I'm actually not even sure if those were used for the rotation of Cartesian frame. Any comments, opinions, replies would be appreciated. Thank you, Carl |
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November 15, 2016, 10:27 |
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#2 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
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Quote:
The name of filtering in that paper is taken from the LES nomenclature. They apply a filtering procedure on the field, that is a way to eliminate wavenumber components of the solution higher than a certain threshold. However, from what I read, they do not perform a true LES with an explicit SGS model but let that the truncation error of the scheme act as model (ILES). I suggest to read the paper of Lele (1992). |
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November 15, 2016, 10:45 |
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#3 | |
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carl jung
Join Date: Mar 2016
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Quote:
Do you have an idea how they rotated the Cartesian frame? I've never learned things like before |
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November 15, 2016, 11:02 |
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#4 | |
Senior Member
Filippo Maria Denaro
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Quote:
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November 15, 2016, 11:06 |
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#5 |
New Member
carl jung
Join Date: Mar 2016
Posts: 15
Rep Power: 10 |
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Tags |
cartesian grid, low pass filter, padé-type filter, revolving wing, rotation |
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