Re: Question on time-marching scheme in Fipy
yes > On Oct 20, 2016, at 10:55 AM, Campbell, Ian > wrote: > > Hi Daniel, > > With regards to your answer: > > "It's fully implicit unless the user sets it up in a different way" > > Just to confirm what I understand from this and from your 2009 paper, alpha > in FiPy is 1.0 by default, and so the fully implicit time-stepping scheme > that's used is backward-Euler, correct? > > With best regards, > > - Ian > > -Original Message- > From: fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] On Behalf Of > Daniel Wheeler > Sent: 19 October 2016 16:26 > To: Multiple recipients of list > Subject: Re: Question on time-marching scheme in Fipy > > Sorry for the slow response, see answers below. > > On Mon, Oct 10, 2016 at 6:08 PM, Gopalakrishnan, Krishnakumar > wrote: >> >> However, my questions are more general, to be executed when updateOld() is >> called. >> >> · What’s the default implicit scheme in fipy? > > It's fully implicit unless the user sets it up in a different way. > >> · How does one go about implementing a specific 2nd order >> time-stepping scheme such as (Adams-Bashforth, BDF etc.) > > We don't have any easy way to do higher order time stepping right now and I'm > not aware of any attempts to do so. > >> · Is there any way to use the FVM only for the spatial >> discretisation, i.e. use a method of lines approach for the time-stepping ? > > It might be possible with source terms, but I haven't tried. > >> I apologise if the questions sound too basic here. I am just curious about >> understanding fipy’s default scheme and implementing an own time-stepper. > > It's a very good question, but I don't have any helpful answers. > > -- > Daniel Wheeler > > ___ > fipy mailing list > fipy@nist.gov > http://www.ctcms.nist.gov/fipy > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] > > ___ > fipy mailing list > fipy@nist.gov > http://www.ctcms.nist.gov/fipy > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] ___ fipy mailing list fipy@nist.gov http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
RE: Question on time-marching scheme in Fipy
Hi Daniel, With regards to your answer: "It's fully implicit unless the user sets it up in a different way" Just to confirm what I understand from this and from your 2009 paper, alpha in FiPy is 1.0 by default, and so the fully implicit time-stepping scheme that's used is backward-Euler, correct? With best regards, - Ian -Original Message- From: fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] On Behalf Of Daniel Wheeler Sent: 19 October 2016 16:26 To: Multiple recipients of list Subject: Re: Question on time-marching scheme in Fipy Sorry for the slow response, see answers below. On Mon, Oct 10, 2016 at 6:08 PM, Gopalakrishnan, Krishnakumar wrote: > > However, my questions are more general, to be executed when updateOld() is > called. > > · What’s the default implicit scheme in fipy? It's fully implicit unless the user sets it up in a different way. > · How does one go about implementing a specific 2nd order > time-stepping scheme such as (Adams-Bashforth, BDF etc.) We don't have any easy way to do higher order time stepping right now and I'm not aware of any attempts to do so. > · Is there any way to use the FVM only for the spatial > discretisation, i.e. use a method of lines approach for the time-stepping ? It might be possible with source terms, but I haven't tried. > I apologise if the questions sound too basic here. I am just curious about > understanding fipy’s default scheme and implementing an own time-stepper. It's a very good question, but I don't have any helpful answers. -- Daniel Wheeler ___ fipy mailing list fipy@nist.gov http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] ___ fipy mailing list fipy@nist.gov http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
Re: Question on time-marching scheme in Fipy
Sorry for the slow response, see answers below. On Mon, Oct 10, 2016 at 6:08 PM, Gopalakrishnan, Krishnakumar wrote: > > However, my questions are more general, to be executed when updateOld() is > called. > > · What’s the default implicit scheme in fipy? It's fully implicit unless the user sets it up in a different way. > · How does one go about implementing a specific 2nd order > time-stepping scheme such as (Adams-Bashforth, BDF etc.) We don't have any easy way to do higher order time stepping right now and I'm not aware of any attempts to do so. > · Is there any way to use the FVM only for the spatial > discretisation, i.e. use a method of lines approach for the time-stepping ? It might be possible with source terms, but I haven't tried. > I apologise if the questions sound too basic here. I am just curious about > understanding fipy’s default scheme and implementing an own time-stepper. It's a very good question, but I don't have any helpful answers. -- Daniel Wheeler ___ fipy mailing list fipy@nist.gov http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
Question on time-marching scheme in Fipy
Hello, I have a pretty naïve question about the time-marching scheme used within fipy. In general, we step through time using a while loop, with some dt. However, I am quite interested in knowing about the specific time-stepping scheme itself. I know that mesh.examples.diffusion.mesh1D explained a bit about implicit vs explicit schemes and how to obtain a Crank-Nicholson scheme by adding EqI & EqX. However, my questions are more general, to be executed when updateOld() is called. · What's the default implicit scheme in fipy? · How does one go about implementing a specific 2nd order time-stepping scheme such as (Adams-Bashforth, BDF etc.) · Is there any way to use the FVM only for the spatial discretisation, i.e. use a method of lines approach for the time-stepping ? I apologise if the questions sound too basic here. I am just curious about understanding fipy's default scheme and implementing an own time-stepper. Best Regards Krishna ___ fipy mailing list fipy@nist.gov http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
