[Users] separation of simulation domain

[林家暉]

Dear Roland,

I see.

Thanks for your information.

Best regards,
Chia-Hui
________________________________
寄件者: Roland Haas <rhaas at illinois.edu>
寄件日期: 2018年10月11日 下午 08:32:49
收件者: 林家暉
副本: Einstein Toolkit Users
主旨: Re: [Users] separation of simulation domain

Hello Chia-Hui,

> I have a question about whether it is possible to separate the domain
> of the simulation.  I want to simulate with a larger scale such as (1
> million km )^3 , however it is too computation-consuming to simulate
> the whole domain with GR and it is not necessary to consider GR
> because GR could be ignored in such large scale. But in the region
> near center with high density , GR is important .
Right now there is no way in Cactus to only allocate memory for some
variables in one region of the grid but allocate memory for all of them
in other regions.

> Therefore I am wondering if it is possible that GR is included in the
> center region ,say (1000 km)^3, but not included in the other region.
> However another problem is that timescale is also very different.
> ET's time scale is about ~ ms but what I need is around hours to
> days. Is there some suggestion for me to deal with it ?
That will always be difficult. With mesh refinement you can add
resolution in only the regions where high spatial and temporal
resolution is required and because Carpet implements sub-cycling in
time, in regions where only the coarse levels exist time steps forward
with the coarse timesteps and not with the fine one.

You could also consider using Llama to have central region with high
(Cartesian) resolution and an other spherical region with lower
resolution.

Yours,
Roland

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