Re: [Libmesh-users] Select quadrature rule order based on element type

[Vikram G. <vik...@gm...>]

Hi Yuxiang, glad to hear you are getting the expected results. This change
looks correct for your case and should not affect the assembly time by a
significant amount. You could also check for the actual type of element
(QUAD4 or TRI) instead of checking indirectly via the number of nodes.

You can check the performance change by checking the performance log which
is included at the end of the program's output. Look for something like:

| System
                                           |
|   assemble()                       1          0.0014      0.001422
 0.0028      0.002767    17.59    34.22    |

Thanks.
Vikram Garg

vikramvgarg.github.io/


On Sun, Apr 14, 2019 at 5:22 PM Yuxiang Wang <yw...@vi...> wrote:

> Hi Vikram,
>
> Thank you for your response!
>
> I didn't think about that - I tried to add that inside the loop over
> elements and got the correct results!
>
> Question - do you think that will significantly slow down the assembly,
> because we are now creating qrule and attaching it for every element loop?
>
> What I did was the following:
>
> for (const auto & elem : mesh.active_local_element_ptr_range()) {
>
> const unsigned int n_nodes = elem->n_nodes();
>
> Order qrule_order;
>
> switch (n_nodes)
> {
> case 3:
> qrule_order = SECOND;
> break;
>
> case 4:
> qrule_order = THIRD;
> break;
>
> default:
> qrule_order = fe_type.default_quadrature_order();
> break;
> }
>
> QGauss qrule (dim, qrule_order);
> fe->attach_quadrature_rule (&qrule);
>
> Thanks!
>
> Best,
> Shawn
>
> On Sun, Apr 14, 2019 at 2:53 PM Vikram Garg <vik...@gm...>
> wrote:
>
>> Hi Yuxiang,
>>                    It should be possible to move the construction of the
>> finite element and the specification of the quadrature rule inside the loop
>> over elements. Did this give any errors, or is otherwise unfeasible for
>> performance reasons ?
>>
>> Thanks.
>> Vikram Garg
>>
>> vikramvgarg.github.io/
>>
>>
>> On Sun, Apr 14, 2019 at 4:30 PM Yuxiang Wang <yw...@vi...> wrote:
>>
>>> Dear all,
>>>
>>> Sorry for the spam.
>>>
>>> I have a mix of QUAD4 and TRI3 elements in my mesh, and would like to use
>>> different quadrature rule orders for each type. Specifically, I'd like to
>>> have order THIRD for QUAD4 and SECOND for TRI3. By default, the orders
>>> are
>>> both THIRD.
>>>
>>> In most examples, I noticed that the specification of qrule is only for
>>> the
>>> entire FEType and not dependent on the element type (e.g. QUAD4 vs TRI3).
>>> Could you please share with me some hints on how to make
>>> element-dependent
>>> qrule order selection happen?
>>>
>>> Best,
>>> Shawn
>>>
>>>
>>> --
>>> Yuxiang "Shawn" Wang, PhD
>>> yw...@vi...
>>> +1 (434) 284-0836
>>>
>>> _______________________________________________
>>> Libmesh-users mailing list
>>> Lib...@li...
>>> https://lists.sourceforge.net/lists/listinfo/libmesh-users
>>>
>>
>
> --
> Yuxiang "Shawn" Wang, PhD
> yw...@vi...
> +1 (434) 284-0836
>