[petsc-users] PETSc DS Auxiliary Variable Question

Tue May 15 19:53:24 CDT 2018

OK, I may as well just say that this is something that has never been quite
clear to me. From what it looks, the auxiliary terms tend to denote
material properties, or similar spatial varying terms. However, judging
from the existence of both the 'constants' vector, as well as the
derivative vectors of the auxiliary variables with respect to time and
space in the callback call, I am going to guess that it can be used with
time dependent terms as well.

What I am looking to do is find some way to take the gradient of a first
temporal derivative of a variable (displacement), and access this result
within one of the residual callback functions that provides input to
PetscDSSetResidual. Maybe there is another way to do this (probably.) Any
thoughts would be appreciated.

Robert L. Walker
MS Petroleum Engineering
Mork Family Department of Chemicals and Materials Sciences
University of Southern California
----------------------------------------------
Mobile US: +1 (213) - 290 -7101
Mobile EU: +34 62 274 66 40
rlwalker at usc.edu

On Tue, May 15, 2018 at 5:25 PM, Robert Walker <rlwalker at usc.edu> wrote:

> Sounds like a lovely place to look again.
>
> sent from an overpriced pocket calculator
>
> On Tue, May 15, 2018, 17:21 Matthew Knepley <knepley at gmail.com> wrote:
>
>> On Tue, May 15, 2018 at 8:11 PM, Robert Walker <rlwalker at usc.edu> wrote:
>>
>>> Hello,
>>>
>>> I am writing a program using PETScDS along with PETScFE and PETScTS in a
>>> similar vein to TS examples 45 - 48. I seek to use the auxiliary variables
>>> accessed by the pointwise functions in a manner similar to how I understand
>>> that MOOSE handles auxiliary variables, that is that in the following:
>>>
>>> f0(PetscInt <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscInt.html-23PetscInt&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=ZdjNjMAEKJBaB6tdYtlF8OtnD_BYW-T126vR8rJ60_Y&e=> dim, PetscInt <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscInt.html-23PetscInt&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=ZdjNjMAEKJBaB6tdYtlF8OtnD_BYW-T126vR8rJ60_Y&e=> Nf, PetscInt <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscInt.html-23PetscInt&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=ZdjNjMAEKJBaB6tdYtlF8OtnD_BYW-T126vR8rJ60_Y&e=> NfAux,
>>>
>>>    const PetscInt <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscInt.html-23PetscInt&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=ZdjNjMAEKJBaB6tdYtlF8OtnD_BYW-T126vR8rJ60_Y&e=> uOff[], const PetscInt <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscInt.html-23PetscInt&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=ZdjNjMAEKJBaB6tdYtlF8OtnD_BYW-T126vR8rJ60_Y&e=> uOff_x[], const PetscScalar <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscScalar.html-23PetscScalar&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=AvpfRlVzQ_jVV9WeiPlpWqnfqUWy23WwV8VL8b-0yrU&e=> u[], const PetscScalar <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscScalar.html-23PetscScalar&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=AvpfRlVzQ_jVV9WeiPlpWqnfqUWy23WwV8VL8b-0yrU&e=> u_t[], const PetscScalar <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscScalar.html-23PetscScalar&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=AvpfRlVzQ_jVV9WeiPlpWqnfqUWy23WwV8VL8b-0yrU&e=> u_x[],
>>>
>>>    const PetscInt <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscInt.html-23PetscInt&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=ZdjNjMAEKJBaB6tdYtlF8OtnD_BYW-T126vR8rJ60_Y&e=> aOff[], const PetscInt <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscInt.html-23PetscInt&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=ZdjNjMAEKJBaB6tdYtlF8OtnD_BYW-T126vR8rJ60_Y&e=> aOff_x[], const PetscScalar <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscScalar.html-23PetscScalar&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=AvpfRlVzQ_jVV9WeiPlpWqnfqUWy23WwV8VL8b-0yrU&e=> a[], const PetscScalar <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscScalar.html-23PetscScalar&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=AvpfRlVzQ_jVV9WeiPlpWqnfqUWy23WwV8VL8b-0yrU&e=> a_t[], const PetscScalar <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscScalar.html-23PetscScalar&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=AvpfRlVzQ_jVV9WeiPlpWqnfqUWy23WwV8VL8b-0yrU&e=> a_x[],
>>>
>>>    PetscReal <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscReal.html-23PetscReal&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=9tKMcRlCN8VCOX2wc7_KpmRHOuXOAnS4-dYYlcHvAXI&e=> t, const PetscReal <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscReal.html-23PetscReal&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=9tKMcRlCN8VCOX2wc7_KpmRHOuXOAnS4-dYYlcHvAXI&e=> x[], PetscScalar <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscScalar.html-23PetscScalar&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=AvpfRlVzQ_jVV9WeiPlpWqnfqUWy23WwV8VL8b-0yrU&e=> f0[])
>>>
>>>
>>> some indices of the a[] array may hold values generated using the
>>> primary variable values of the prior iteration, or may simply point to the
>>> primary variables themselves.
>>>
>>> What is the best way to go about this? Apologies if this is either quite
>>> obvious or has been extensively addressed before.
>>>
>>
>> Not sure where I need to start. First, do you understand how the
>> auxiliary variables are being used in SNES ex12 or ex69?
>>
>>   Thanks,
>>
>>     Matt
>>
>>
>>> Thank you
>>>
>>>
>>> Robert L. Walker
>>> MS Petroleum Engineering
>>> Mork Family Department of Chemicals and Materials Sciences
>>> University of Southern California
>>> ----------------------------------------------
>>> Mobile US: +1 (213) - 290 -7101
>>> Mobile EU: +34 62 274 66 40
>>> rlwalker at usc.edu
>>>
>>
>>
>>
>> --
>> 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/
>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.caam.rice.edu_-7Emk51_&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=BWOpUsAp5dvI5cUiP4uZxQ&m=WqHFdWvXkjvOoNncNHem23n6BSEqrB0SuZChLaVmvtw&s=Gti6BLze7sGAVpo0fvZMevH2ptQyOSWf_UwOK3jcxPE&e=>
>>
>
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