[Gmsh] High-Order Meshing

[Jean-François Remacle]

Le 11 déc. 2013 à 11:53, George Ntemos <george.ntemos11 at imperial.ac.uk> a écrit :

> Dear Gmsh Development Team,
> 
> 
> My name is George Ntemos and I am a PhD student in the Aeronautics Department of Imperial College London. Our team is developing and applying CFD software, using gmsh for high-order meshing purposes.
> I am currently studying a flow case around a rod-aerofoil set-up and I've been experiencing some problems with high-order meshing. More specifically, the meshing algorithm fails to mesh in high order around the (spline-defined) aerofoil profile. Please find attached a lightweight .geo file of my configuration just for demonstration purposes. If one tries meshing this file in 3d and for order > 1, gmsh will warn that, to my understanding, the algorithm fails to properly converge at certain points, visibly resulting in quite severe discrepancies for a few elements (curvilinear on). It also warns that it cannot orient the normal for the two extruded surfaces of the rod (cylinder) boundary layer. It is worth noting here that I am experiencing none of the above problems when I am meshing in 2d. Since my 3d mesh is just a simple extrusion, I would assume that extending to 3d is just a trivial case of translating every operation along the 3rd dimension. I am of course not particularly experienced in using gm

The 2D mesh is already wrong as is. If you use the high order tools with the current parameters, this
is what it gives : 

Info    : --- Optimization pass with initial jac. range (-0.528961, 1.76584), jacBar = -0.581857
Info    : Reached jacobian (0.148494 1.77654) requirements, setting null gradient
Info    : Optimization finalized after 11 iterations (41 function evaluations),
Info    : because gradient norm is no more than EpsG
Info    : Optimization done Range (0.148494,1.77654)
Info    : Optimization succeeded
Info    : Done optimizing high order mesh (278.816 s)

It is quite long indeed (work clearly in progress for boundary layers) but it worked !

JF

> sh however and I may very well be missing something here.
> Any help regarding these issues would be greatly appreciated.
> Thank you for your time.
> 
> Best regards,
> George
> <rod_aerofoil_3d_light.geo>_______________________________________________
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Prof. Jean-Francois Remacle
Universite catholique de Louvain (UCL)
Ecole Polytechnique de Louvain (EPL) - Louvain School of Engineering
Institute of Mechanics, Materials and Civil Engineering (iMMC)
Center for Systems Engineering and Applied Mechanics (CESAME)
Tel : +32-10-472352 -- Mobile : +32-473-909930 

 




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