[FLASH-USERS] [EXTERNAL] Re: Adaptive timestep

[Messer II, Bronson]

Hi Sean, Matuesz, et al., 

Sean is right both about not having sub-cycling in the current solvers and about the desire to change that in the future for FLASH5. 

So, I guess I didn’t have a different opinion at all, just felt the need to chime in. :)

Bronson

> On Oct 1, 2019, at 11:33 AM, Sean M. Couch <couch at pa.msu.edu> wrote:
> 
> Hi Mateusz,
> 
> I will venture my view of this and others can chime in if they have a different opinion. Also, I’m assuming by adaptive timestep you mean sub-cycling in time where different refinement levels take different time steps? 
> 
> For FLASH5, we are transitioning to the AMReX package. AMReX is built on the idea of time sub-cycling so in principle, we could utilize that. For that matter, PARAMESH was also built to allow time sub-cycling, we just never used it. As of now, for the solvers we are porting to FLASH5/AMReX we are still making the assumption of a single global time step. This simplifies things considerably. But I am of the opinion that, eventually, we should implement time sub-cycling and take advantage of what AMReX offers in that regard. This, however, will not likely be a feature available from the outset. 
> 
> Now, what might speed things along is capable developers willing to lend a hand in the implementation ;) 
> 
> Sean
> 
> ----------------------------------------------------------------------
> Sean M. Couch, Ph.D.
> Assistant Professor
> Department of Physics and Astronomy
> Department of Computational Mathematics, Science, and Engineering
> Facility for Rare Isotope Beams
> Michigan State University
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> On Sep 30, 2019, 7:55 PM -0400, Mateusz Ruszkowski <mateuszr at umich.edu>, wrote:
>> 
>> 
>> Hi all,
>> 
>> Does anyone know if there a plan to extend FLASH to include adaptive timestep or if users would be interested in such a code feature?
>> Myself and a number of my collaborators would definitely be interested in using such a code capability.
>> 
>> Cheers,
>> Mateusz
>>