[Gmsh] High-Order Meshing

[Thomas Toulorge]

Dear George,

You can also use the "Fast Curving" algorithm in the "High order tools" 
after converting your 3D mesh to high order. It is still 
work-in-progress and not guaranteed to work, specially for order > 2, 
but for the case you sent, it corrects the invalid 2nd-order 3D mesh in 
less than 2 seconds.

Best regards,

Thomas


On 12/13/2013 02:14 PM, Jean-François Remacle wrote:
>
> Le 11 déc. 2013 à 11:53, George Ntemos <george.ntemos11 at imperial.ac.uk 
> <mailto: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 3^rd 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
>
>
>
>
>
>
>

-- 
Thomas Toulorge
Université catholique de Louvain (UCL)
Institute of Mechanics, Materials and Civil Engineering (iMMC)
Applied Mechanics and Mathematics Division (MEMA)
Avenue George Lemaître 4-6 bte L4.05.02
1348 Louvain-la-Neuve, BELGIUM
Tel.: +32 10 47 23 54

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