I would be happy to do the comparison and make the fix. But before doing
that, I want to make sure I understand the formula correctly.
When we calculate the rotation matrix, it seems that the *du* (incremental
displacement) is used.
// Then initialize the <code>FEValues</code> object on the present
// cell, and extract the gradients of the displacement at the
// quadrature points for later computation of the strains
fe_values.reinit(cell);
fe_values.get_function_gradients(incremental_displacement,
displacement_increment_grads);
Should we use the *velocity *([image: \vec{v} = \frac{d \vec{u}}{dt}]),
since [image: \vec{\omega} = \frac{1}{2}\nabla \times \vec{v} =
\frac{1}{2}\nabla \times \frac{d\vec{u}}{dt}] ?
Can you check this as well?
Best,
Michael
On Sat, Jun 26, 2021 at 1:48 AM Jean-Paul Pelteret <jppelte...@gmail.com>
wrote:
> Following Andrew’s explanation, I suppose that this is relation for which
> we’re lacking the factor of 1/2, right?
>
>
> https://en.wikipedia.org/wiki/Angular_velocity#Angular_velocity_as_a_vector_field
>
> If so, then maybe we should link to this equation in the tutorial
> documentation too.
>
> If this is wrong in the deal.II code, would you be interested in writing a
> patch to correct this? It should be an easy fix, and a good first patch to
> contribute to the library!
>
>
> I concur — it would be great if you’d be willing to write a patch that
> fixes this! It would be interesting to see the effect on the results of the
> tutorial.
>
> Best,
> Jean-Paul
>
>
> On 26. Jun 2021, at 05:58, Wolfgang Bangerth <bange...@colostate.edu>
> wrote:
>
> On 6/24/21 6:32 PM, Michael Li wrote:
>
> Andrew, thanks for confirming that. The missing 1/2 does not affect the
> demonstration of functionalities of deal.II but it may change the results.
>
>
> If this is wrong in the deal.II code, would you be interested in writing a
> patch to correct this? It should be an easy fix, and a good first patch to
> contribute to the library!
>
> If you're curious about ho to write a patch, take a look at
> https://github.com/dealii/dealii/wiki/Contributing
>
> Best
> W.
>
>
>
On Sat, Jun 26, 2021 at 1:48 AM Jean-Paul Pelteret <jppelte...@gmail.com>
wrote:
> Following Andrew’s explanation, I suppose that this is relation for which
> we’re lacking the factor of 1/2, right?
>
>
> https://en.wikipedia.org/wiki/Angular_velocity#Angular_velocity_as_a_vector_field
>
> If so, then maybe we should link to this equation in the tutorial
> documentation too.
>
> If this is wrong in the deal.II code, would you be interested in writing a
> patch to correct this? It should be an easy fix, and a good first patch to
> contribute to the library!
>
>
> I concur — it would be great if you’d be willing to write a patch that
> fixes this! It would be interesting to see the effect on the results of the
> tutorial.
>
> Best,
> Jean-Paul
>
>
> On 26. Jun 2021, at 05:58, Wolfgang Bangerth <bange...@colostate.edu>
> wrote:
>
> On 6/24/21 6:32 PM, Michael Li wrote:
>
> Andrew, thanks for confirming that. The missing 1/2 does not affect the
> demonstration of functionalities of deal.II but it may change the results.
>
>
> If this is wrong in the deal.II code, would you be interested in writing a
> patch to correct this? It should be an easy fix, and a good first patch to
> contribute to the library!
>
> If you're curious about ho to write a patch, take a look at
> https://github.com/dealii/dealii/wiki/Contributing
>
> Best
> W.
>
>
> --
> ------------------------------------------------------------------------
> Wolfgang Bangerth email: bange...@colostate.edu
> <bange...@colostate.edu>
> www: http://www.math.colostate.edu/~bangerth/
>
> --
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