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<div dir="auto">I should have just sent you the descriptions below. Hopefully they are not too confusing (I think I wrote them…).
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<div dir="auto">The answer to your question is Yes, the first refinement reduction will occur after `t=gr_lrefineMaxRedTRef+gr_lrefineMaxRedTimeScale`. </div>
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<div dir="auto">Sean</div>
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<pre style="margin-top: 0px; margin-bottom: 0px; padding: 0px; caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">gr_lrefineMaxRedDoByLogR [BOOLEAN] [FALSE]
Softly force effectively a lower lrefine_max depending on distance from
center. See gr_lrefineMaxRedRadiusFact.
gr_lrefineMaxRedDoByTime [BOOLEAN] [FALSE]
Lower the effective lrefine_max as a function of time. See runtime
parameters gr_lrefineMaxRedTRef, gr_lrefineMaxRedTimeScale, and
gr_lrefineMaxRedLogBase.
gr_lrefineMaxRedLogBase [REAL] [10.0]
Valid Values: 1.0 to INFTY
Logarithm base for determining when repeated reductions in effective
lrefine_max should happen. The nth reduction will happen at
t=gr_lrefineMaxRedTRef+gr_lrefineMaxRedTimeScale*gr_lrefineMaxRedLogBase**(n-1).
gr_lrefineMaxRedRadiusFact [REAL] [0.0]
Valid Values: 0.0 to INFTY
factor that determines a minimum resolution (and thus maximum refinement
level) based on distance from a center. See x_refine_center,
y_refine_center, z_refine_center for the center coordinates. This is
approximately (linearly) equivalent to requiring a minimum *angular*
resolution, within the limits set by the global lrefine_min and
lrefine_max. Only used when gr_lrefineMaxRedDoByLogR is TRUE.
gr_lrefineMaxRedTRef [REAL] [0.0]
Valid Values: Unconstrained
reference time for time-based max level reduction. The effective
reduction of lrefine_max only kicks in for times greater than
gr_lrefineMaxRedTRef. The first time lrefine_max is effectively lowered
actually happens at t=gr_lrefineMaxRedTRef+gr_lrefineMaxRedTimeScale.
gr_lrefineMaxRedTimeScale [REAL] [1.0]
Valid Values: TINY to INFTY
the time scale for effectively lowering lrefine_max: The first reduction
takes place at t=gr_lrefineMaxRedTRef+gr_lrefineMaxRedTimeScale.</pre>
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Sean M. Couch, Ph.D.</div>
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On May 30, 2019, 10:35 AM -0400, Slavin, Jonathan <jslavin@cfa.harvard.edu>, wrote:<br>
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Hi Sean,</div>
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Yes sounds like what I'm after. I'll have to look into how to use those for my case. If I were to use the time one, would it de-resolve the highly resolved regions after the given time is reached?</div>
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Jon</div>
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<div dir="ltr" class="gmail_attr">On Thu, May 30, 2019 at 10:28 AM Sean M. Couch <<a href="mailto:couch@pa.msu.edu">couch@pa.msu.edu</a>> wrote:<br>
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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>
<div dir="auto"><br>
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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>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>
<div dir="auto"><br>
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<div class="gmail-m_3701072861921165815matchFont">----------------------------------------------------------------------
<div style="font-size:14px;font-family:-apple-system,BlinkMacSystemFont,sans-serif">
Sean M. Couch, Ph.D.</div>
<div style="font-size:14px;font-family:-apple-system,BlinkMacSystemFont,sans-serif">
Assistant Professor</div>
<div style="font-size:14px;font-family:-apple-system,BlinkMacSystemFont,sans-serif">
Department of Physics and Astronomy</div>
<div style="font-size:14px;font-family:-apple-system,BlinkMacSystemFont,sans-serif">
Department of Computational Mathematics, Science, and Engineering</div>
<div style="font-size:14px;font-family:-apple-system,BlinkMacSystemFont,sans-serif">
Facility for Rare Isotope Beams</div>
<div style="font-size:14px;font-family:-apple-system,BlinkMacSystemFont,sans-serif">
Michigan State University</div>
<div style="font-size:14px;font-family:-apple-system,BlinkMacSystemFont,sans-serif">
567 Wilson Rd, 3250 BPS</div>
<div style="font-size:14px;font-family:-apple-system,BlinkMacSystemFont,sans-serif">
East Lansing, MI 48824</div>
<div style="font-size:14px;font-family:-apple-system,BlinkMacSystemFont,sans-serif">
(517) 884-5035 --- <a href="mailto:couch@pa.msu.edu" target="_blank">couch@pa.msu.edu</a> ---
<a href="http://www.pa.msu.edu/~couch" target="_blank">www.pa.msu.edu/~couch</a></div>
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<div name="messageReplySection" style="font-size:14px;font-family:-apple-system,BlinkMacSystemFont,sans-serif">
On May 29, 2019, 1:45 PM -0400, Slavin, Jonathan <<a href="mailto:jslavin@cfa.harvard.edu" target="_blank">jslavin@cfa.harvard.edu</a>>, 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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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small">
Regards,</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small">
Jon</div>
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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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--<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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