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<div dir="auto">Hi Jon,
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<div dir="auto">Depending on what exactly you are looking to do, it might already be possible with FLASH. FLASH4 already has the capability to reduce the maximum allowed refinement level as a function of radius. See the runtime parameter `gr_lrefineMaxRedDoByLogR`
and `gr_lrefineMaxRedRadiusFact`. The latter is a bit arcane, but essentially sets the “angular” resolution of the resulting grid. But the value chose depends on the number of zones per block (`nxb`) since the resolution limiting is actually based on the _block_
size, not the _zone_ size directly. </div>
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<div dir="auto">The second already-implemented feature that could be of use here is the runtime param `gr_lrefineMaxRedDoByTime`. This, if True, decreases the maximum allowed refinement level anywhere on the grid as a function of time. The behavior is set by
the params `gr_lrefineMaxRedLogBase`, `gr_lrefineMaxRedTRef`, and `gr_lrefineMaxRedTimeScale`. See appropriate documentation online or the code directly. Combined with `<span style="caret-color: rgb(213, 218, 222);">gr_lrefineMaxRedDoByLogR`, this means you
can “de-resolve” the inner region of your grid as the feature you are interested in moves out in radius. This nets you not only a reduction in the total number of zones in the simulation but, usually, a nice increase in the time step size. We have been using
these features, in various combinations, for years in our supernova simulations. </span></div>
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<div dir="auto">This all assumes that you are included the “large” scale region from the very start of your simulation. If you want to map an already-run simulation into a larger domain, literally zooming out, that’s harder. I did it a long time ago (with FLASH
v2!) when I was a grad student but that code and capability are now part of the geological record, I fear. </div>
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<div dir="auto">Sean</div>
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On May 29, 2019, 1:45 PM -0400, Slavin, Jonathan <jslavin@cfa.harvard.edu>, wrote:<br>
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Hi all,</div>
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Often simulators will use zoom-in simulations - taking a part of a large simulation to focus on a small region of interest. I would like to do the opposite. I would like to take a fairly small scale simulation and embed it in a larger smooth background and
reduce the refinement by a level or two. I imagine that this will require some significant coding, but I was wondering if anyone had tried something like this or could offer suggestions on how to do it. Thanks in advance for any help.</div>
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Regards,</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small">
Jon</div>
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--<br>
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<div dir="ltr"><img src="https://lh6.googleusercontent.com/mJuf9zI6QC5w6HPVCinnLSkpp-RgufOfl7nw1E_aghDflNhusoRbZTuP_0x-RkECQRhIfvPxGMe6zSt6chyXZ7D5DdqtkZPp0q-TE8itKny8VWObWAiZ1aurYWDO0CtZgvJEXfzu" width="350" height="2" style="font-size:12.6667px;font-family:Arial;white-space:pre-wrap;border:none"></div>
<div dir="ltr">Jonathan D. Slavin</div>
<div dir="ltr">Astrophysicist - High Energy Astrophysics Division</div>
<div dir="ltr">Center for Astrophysics | Harvard & Smithsonian</div>
<div dir="ltr">Office: (617) 496-7981 | Cell: (781) 363-0035<br>
60 Garden Street | MS 83 | Cambridge, MA 02138</div>
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