[petsc-users] PetscFEIntegrateBdResidual_Basic

[David Fuentes]

Thanks! will give that a try!
df

On Mon, Nov 20, 2017 at 11:23 AM, Matthew Knepley <knepley at gmail.com> wrote:

> On Mon, Nov 20, 2017 at 12:20 PM, David Fuentes <fuentesdt at gmail.com>
> wrote:
>
>> Thanks for the quick reply. Indeed it does work like this. I have added a
>> location dependence on the boundary to differentiate the two. However, when
>> my mesh moves then the BC will be applied incorrectly.
>>
>
> I don't think you should have to do that. You can call AddBoundary twice.
> Once with a function with the first branch and marker value 3, and the next
> with the second branch and marker value 2. Does
> that make sense?
>
>   Thanks,
>
>      Matt
>
>> *//  PetscFEIntegrateBdResidual_Basic DMPlexComputeBdResidual_Internal*
>>
>> *static* *void** f0_bd_u(PetscInt dim, PetscInt Nf, PetscInt NfAux,*
>>
>>                     *const** PetscInt uOff[], **const** PetscInt
>> uOff_x[], **const** PetscScalar u[], **const** PetscScalar u_t[], *
>> *const** PetscScalar u_x[],*
>>
>>                     *const** PetscInt aOff[], **const** PetscInt
>> aOff_x[], **const** PetscScalar a[], **const** PetscScalar a_t[], *
>> *const** PetscScalar a_x[],*
>>
>> *                    PetscReal t, **const** PetscReal x[], **const**
>> PetscReal n[], PetscInt numConstants, **const** PetscScalar constants[],
>> PetscScalar f0[])*
>>
>> *{ *
>>
>> *  PetscInt d;*
>>
>>   *double** radius = **0.0**;*
>>
>>   *const* *double**  zthresh = (**3.** - **4.5**/**2.**)***.01**; **//
>> [m]*
>>
>>   *for** (d = **0**; d < **2**; ++d) radius += x[d]*x[d];*
>>
>> *  radius = sqrt(radius); *
>>
>>   *if** ( radius > **.001**/**2.**  ) *
>>
>> *    {f0[**0**] =  constants[**2**] * u[**0**];}*
>>
>>   *else*
>>
>> *    {*
>>
>> *     f0[**0**] = -constants[**3**]       ; *
>>
>> *    }*
>>
>> *} *
>>
>>
>> On Mon, Nov 20, 2017 at 11:02 AM, Matthew Knepley <knepley at gmail.com>
>> wrote:
>>
>>> On Mon, Nov 20, 2017 at 11:46 AM, David Fuentes <fuentesdt at gmail.com>
>>> wrote:
>>>
>>>> *Is there a way to pass the boundary set id to the function pointers
>>>> for the residual evaluation on the boundary ?*
>>>>
>>>> *https://bitbucket.org/petsc/petsc/src/d89bd21cf2b5366df29efb6006298d2bc22fb509/src/dm/dt/interface/dtfe.c?at=master&fileviewer=file-view-default#dtfe.c-4245
>>>> <https://bitbucket.org/petsc/petsc/src/d89bd21cf2b5366df29efb6006298d2bc22fb509/src/dm/dt/interface/dtfe.c?at=master&fileviewer=file-view-default#dtfe.c-4245>*
>>>>
>>>> *I want to pass the boundary condition/constraint ID (ids):
>>>> PetscErrorCode PetscDSAddBoundary(PetscDS ds, DMBoundaryConditionType type,
>>>> const char name[], const char labelname[], PetscInt field, PetscInt
>>>> numcomps, const PetscInt *comps, void (*bcFunc)(void), PetscInt numids,
>>>> const PetscInt *ids, void *ctx)*
>>>>
>>>> *to the functions for the residual evaluation on the boundary.*
>>>>
>>>>
>>>> *For example, I have two side sets in an exodus file. I want to
>>>> implement Neumann boundary conditions on side set = 2 and Mixed/Cauchy BC
>>>> on side set = 3. Or similarly use different*
>>>>
>>>> *gmsh BC tags for Neumann/Mixed BC.*
>>>>
>>> I am not completely against this, but let me respond with my rationale
>>> first. What I thought you would do, is call AddBoundary() twice. Once with
>>> the
>>> Neumann function and value 2, and once with the Cauchy function and
>>> value 3. Does that not work in your situation?
>>>
>>> Also, I am refectoring this right now because a DS object can only take
>>> a single boundary integral point function (which is a pain for
>>> inhomogeneous Neumann),
>>> so I welcome input.
>>>
>>>   Thanks,
>>>
>>>     Matt
>>>
>>> --
>>> What most experimenters take for granted before they begin their
>>> experiments is infinitely more interesting than any results to which their
>>> experiments lead.
>>> -- Norbert Wiener
>>>
>>> https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
>>>
>>
>>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
> https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
>
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