<p>With PETSc, there is a lot more opportunity to change details of the nonlinear and linear solve. You can use CVode through PETSc, but it may also be worth trying the ARK-IMEX and Rosenbrock-W methods that we have implemented, especially if stability near the imaginary axis is useful for you, or if error control is being finnicky with the BDFs. It is easier to experiment with different algorithms in PETSc since most choices can be made at run-time (e.g. command line options).</p>
<p>> On May 4, 2012 6:38 PM, "Alan Sayre" <<a href="mailto:ansayre@sbcglobal.net">ansayre@sbcglobal.net</a>> wrote:<br>
>><br>
>> Barry,<br>
>> <br>
>> Sorry for being imprecise. I haven't started coding anything yet with PETSc. I have only tried the native SUNDIALS Kinsol. I have had good success using the SUNDIALS Cvode for zero-d ode using the ABF mechanism. My purpose in posting is to determine if the PETSc suite of tools is appropriate, there is experience using solving similar problems, etc.<br>
>> <br>
>> Thanks,<br>
>> <br>
>> Alan<br>
>><br>
>> ________________________________<br>
>> From: Barry Smith <<a href="mailto:bsmith@mcs.anl.gov">bsmith@mcs.anl.gov</a>><br>
>> To: PETSc users list <<a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a>><br>
>> Sent: Fri, May 4, 2012 7:06:33 PM<br>
>> Subject: Re: [petsc-users] application of petsc to psr<br>
>><br>
>><br>
>> Alan,<br>
>><br>
>> You have a very complicated model (and presumably discretization) which makes it difficult for us to provide coherent advice. What stage are you in your code at using PETSc? Are you thinking about using PETSc? Have you not started yet? Is it running but not converging with PETSc? There are many reasons that Newton may not converge: see <a href="http://www.mcs.anl.gov/petsc/documentation/faq.html#newton">http://www.mcs.anl.gov/petsc/documentation/faq.html#newton</a><br>
>><br>
>> Barry<br>
>><br>
>><br>
>><br>
>> On May 3, 2012, at 8:02 PM, Alan Sayre wrote:<br>
>><br>
>> > Barry,<br>
>> > <br>
>> > Thanks but that is not quite what I have in mind. The existing PSR model in my CFD code is not converging for PSR models containing the Method of Moments using the ABF mechanism described as shown in the Chemkin 2006 workshop proceedings. I have tried KINSOL and have still not been able to get it to converge. Any assistance in developing a PETSC based solution algorithm is appreciated.<br>
>> > <br>
>> > thanks,<br>
>> > <br>
>> > Alan<br>
>> > <br>
>> > From: Barry Smith <<a href="mailto:bsmith@mcs.anl.gov">bsmith@mcs.anl.gov</a>><br>
>> > To: PETSc users list <<a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a>><br>
>> > Sent: Wed, May 2, 2012 10:54:21 PM<br>
>> > Subject: Re: [petsc-users] application of petsc to psr<br>
>> > <br>
>> > <br>
>> > <a href="http://www.sandia.gov/chemkin/workshop/proceedings/Meeks_CHEMKINWorkshop2006.pdf">http://www.sandia.gov/chemkin/workshop/proceedings/Meeks_CHEMKINWorkshop2006.pdf</a> ?<br>
>> > <br>
>> > <br>
>> > On May 2, 2012, at 9:45 PM, Alan Sayre wrote:<br>
>> > <br>
>> > > I'm new to using PETSc. I need to model perfectly stirred reactors for chemical kinetics (10-1000 species), I welcome recommendations on how to get "up-to-speed". I also need to incorprate solution of the energy (temperature) equation and moments of soot distributions.<br>
>> > > <br>
>> > > Thanks for any suggestions.<br>
>> > > <br>
>> > > Alan<br>
>> > <br>
>><br>
</p>