<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Ah, okay that wasn't clear to me. That will work for this case without cooling, but what this is essentially doing is decreasing the mean mass per particle as a kludge for including electron pressure. When cooling is included then, the number density, n = rho/m, will be too high. I'm referring to optically thin radiative cooling, e.g. using the Sutherland & Dopita cooling curve. In that case what you need is n(H)*n(e). I suppose I could kludge that as well...</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Jon</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Sep 16, 2015 at 11:30 AM, Dean Townsley <span dir="ltr"><<a href="mailto:Dean.M.Townsley@ua.edu" target="_blank">Dean.M.Townsley@ua.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
Hi Johnathan,<br>
<br>
The gamma-law EOS is just a simple ideal gas as described in section
15.2 of the user's guide:<br>
<a href="http://flash.uchicago.edu/site/flashcode/user_support/flash4_ug_4p3/node22.html#SECTION06320000000000000000" target="_blank">http://flash.uchicago.edu/site/flashcode/user_support/flash4_ug_4p3/node22.html#SECTION06320000000000000000</a><br>
<br>
As you can see from the expressions there, zbar is not used at all.
You should set abar so that these expressions give what you expect.
This is what John Zuhone and Tomek I believe are suggesting.<br>
<br>
Hopefully that helps clarify,<br>
Dean<div><div class="h5"><br>
<br>
<br>
<br>
<br>
<div>On 09/16/2015 10:14 AM, Jonathan Slavin
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Yes, that's
exactly what I said. How does one get FLASH to use zbar? I
just tried again after running setup with the added argument</div>
<div class="gmail_default">-with-unit=physics/Eos/EosMain/Gamma<br>
</div>
<div class="gmail_default">but I still get that d*T/P *
kboltz/amu_cgs = 1.28 (= abar) instead of 0.612 (= abar/(1 +
zbar)) like I would expect.</div>
<div class="gmail_default"><br>
</div>
<div class="gmail_default">Jon</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Sep 16, 2015 at 10:23 AM,
Tomasz Plewa <span dir="ltr"><<a href="mailto:tplewa@fsu.edu" target="_blank">tplewa@fsu.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"> Hi Jon -<br>
<br>
It is frequently assumed electron pressure is negligible
compared to ions, which is true for a nonionized gas.
Obviously, the correct formula should take into account
contributions from both ions and electrons. For a fully
ionized gas, <br>
<br>
\mu = \frac{\sum_j n_j A_j }{\sum_j n_j ( 1 + Z_j) }<br>
<br>
Tomek<br>
--
<div>
<div><br>
<div>On 09/16/15 10:00, Jonathan Slavin wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Hi
all,</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">I'm
doing simulations aimed at understanding aspects
of supernova remnant evolution. Since the SNR
is expanding the general interstellar medium,
the proper mean mass per atom (i.e. neutrals and
ions) is about 1.28 amu, given 90% H and 10% He
by number. As I understand it, this is set by
the runtime parameter eos_singleSpeciesA, which
corresponds to abar. If I want to assume
constant, uniform, complete ionization then, as
I understand it, I need to set zbar via the
runtime parameter eos_singleSpeciesZ, to a value
of ~1.091 = 1.2/1.1 = (n(H+) + 2*n(He++))/(n(H)
+ n(He)). At least that's what I thought from
the docs where at one point it's stated that
n(e) = zbar*n(ion). However, when I look at
density*temperature/pressure*kB/amu, I get
abar. So it seems that zbar is not used. What
I expect is that</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">P
= (1 + zbar)/abar*kB*density*temperature</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Where
P is the total pressure (electron pressure +
atom pressure). Is this not true? Do I need to
specify some extra unit for zbar to be used
(maybe -with-unit=physics/Eos/EosMain/Gamma)?
Am I misunderstanding the meaning of zbar? Any
help would be appreciated.</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Thanks,</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Jon</div>
<div><br>
</div>
-- <br>
<div>
<div dir="ltr">
<div>
<div dir="ltr">________________________________________________________<br>
Jonathan D. Slavin
Harvard-Smithsonian CfA<br>
<a href="mailto:jslavin@cfa.harvard.edu" target="_blank">jslavin@cfa.harvard.edu</a>
60 Garden Street, MS 83<br>
phone: <a href="tel:%28617%29%20496-7981" value="+16174967981" target="_blank">(617)
496-7981</a> Cambridge, MA
02138-1516<br>
cell: <a href="tel:%28781%29%20363-0035" value="+17813630035" target="_blank">(781)
363-0035</a> USA<br>
________________________________________________________<br>
<br>
</div>
</div>
</div>
</div>
</div>
</blockquote>
<br>
</div>
</div>
</div>
</blockquote>
</div>
<br>
<br clear="all">
<div><br>
</div>
-- <br>
<div>
<div dir="ltr">
<div>
<div dir="ltr">________________________________________________________<br>
Jonathan D. Slavin Harvard-Smithsonian
CfA<br>
<a href="mailto:jslavin@cfa.harvard.edu" target="_blank">jslavin@cfa.harvard.edu</a>
60 Garden Street, MS 83<br>
phone: <a href="tel:%28617%29%20496-7981" value="+16174967981" target="_blank">(617) 496-7981</a> Cambridge, MA 02138-1516<br>
cell: <a href="tel:%28781%29%20363-0035" value="+17813630035" target="_blank">(781) 363-0035</a> USA<br>
________________________________________________________<br>
<br>
</div>
</div>
</div>
</div>
</div>
</blockquote>
<br>
</div></div></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr">________________________________________________________<br>Jonathan D. Slavin Harvard-Smithsonian CfA<br><a href="mailto:jslavin@cfa.harvard.edu" target="_blank">jslavin@cfa.harvard.edu</a> 60 Garden Street, MS 83<br>phone: (617) 496-7981 Cambridge, MA 02138-1516<br>cell: (781) 363-0035 USA<br>________________________________________________________<br><br></div></div></div></div>
</div>