[Gmsh] Symetry : when it is become explicit ?

[Adrien Girard]

Thank you very much for your answer.

So I have to make the simulation on the whole model (8/8) ? But then the
cost of the simulation will be 8 times more ?
And thus, I do not take benefit of the symmetry of the problem, or
I misunderstood something ?

Thank you


2013/2/6 Rui Maciel <rui.maciel at gmail.com>

>
>
> On 02/05/2013 03:51 PM, Adrien Girard wrote:
>
>> Hello,
>>
>> I just finish university and I am now working as a mechanical engineer and
>> I am still confused with some points of FEM theory.
>>
>> I have to make the complete thermal analysis of a rectangular box, I
>> decided to use the symetry of the problem and thus modelise only 1/8 of
>> the
>> box. But now, I wonder when I have to add the symetry to the problem.
>>
>> - 1) to the mechanical model ? (before the simulation)
>> - 2) at the simulation phase ?
>> - 3) only for the post process, to visualise the result ?
>>
>
> It's the 1st one: before the simulation.
>
> The main point of taking advantage of a model's symmetry is to cut down
> the computational costs of getting a solution to the problem it describes.
>  In your example, if you only analyze 1/8th of a thermal model then it will
> have approximately 1/8th of the degrees of freedom that it would otherwise
> require.  Considering that the computational complexity of the algorithms
> which dominate the whole computational process, as it tends to lie
> somewhere between either O(n^2) or O(n^3), (n) being the number of degrees
> of freedom, you can get an idea of how much more efficient the whole
> process becomes.
>
> Taking advantage of a model's symmetry can also eases the computational
> requirements of the whole visualization process, but in general, when
> compared with the previous point, this detail is pretty much a non-issue.
>  There are plenty of ways to skin this proverbial cat, and symmetry doesn't
> tend to come up in the conversation.
>
>
> Hope this helps,
> Rui Maciel
>
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-- 
Adrien Girard

GSM : 0031 615 355 049
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