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Tips on using mesh stiffness for mesh deformations

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Old   February 21, 2005, 05:34
Default Tips on using mesh stiffness for mesh deformations
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Ste Lakey
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I am trying to analyse an aerofoil which is flapping up and down in CFX. I have managed to implement the mesh deformation in the simulation, however after a number of timesteps in the simulation the solver terminates with errors indicating a negative element volume in the mesh. Any suggestions on the proper use of setting the mesh stiffness to avoid this would be much appreciated as I kind seem to find much in the manuals regarding the use of proper units and numerical values.

Thanks in advance.
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Old   February 21, 2005, 17:32
Default Re: Tips on using mesh stiffness for mesh deformat
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Glenn Horrocks
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Hi,

Mesh stiffness only has an effect if it varies. That is if you set a constant value for the entire domain then all nodes are equally free to move. To make it have an effect you need to make it vary over the domain. As described in the documentation, two useful methods include setting it to either 1 [m^3 s^-1]/Wall Distance, or 1 [m^5 s^-1]/Volume of Finite Volumes. This causes the elements near walls or small elements respectively to become stiffer than the general mesh. When carefully chosen it can help maintain mesh quality and reduce elements inverting. Have a read of Solver Modelling/Basic Capabilities modelling/Mesh Deformation in the documentation.

Glenn Horrocks
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Old   June 17, 2009, 15:44
Default How can I define the mesh stiffness in CFX ?
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How can I define the mesh stiffness in CFX ? CCL object how define this object


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