[yt-users] Athena units

[John ZuHone]

Hi Stephanie,

In general, fields with the normal Athena names will be in code units, whereas the yt names will always be in cgs.

Roughly, it goes like this:

Density = cgs, density = code units
Pressure = cgs, pressure = code units
B[xyz] = cgs, cell_centered_B_[xyz] = code units
[xyz]-velocity = cgs, velocity_[xyz] = code units
momentum_[xyz] = code units

Note that the names are case-sensitive. Now, in yt-3.0 we will be adopting a different set of field names, but for now this should be good.

Best,

John

Sent from John ZuHone's iPad

> On Nov 21, 2013, at 8:43 PM, Stephanie Tonnesen <stonnes at gmail.com> wrote:
> 
> I am now looking at a few more variables, and am not sure whether I should be getting code units or physical units.  In the Athena vtk file, Pressure is one of the variables--will this be plotted in code units or will yt attempt to give me physical units since I am inputting some physical unit conversions in the load command?  Also , is "BMagnitude" in code units?  I am loading my data using the command:
> 
> 
> pf = load("id0/rps."+outstring[i]+"
> .vtk",parameters={"TimeUnits":9.78262,"LengthUnits":8.0236e22,"DensityUnits":9.999e-30})
> 
> 
> Thanks!
> 
> Stephanie
> 
> 
> 
>> On Mon, Oct 21, 2013 at 10:20 PM, Stephanie Tonnesen <stonnes at gmail.com> wrote:
>> Hi Again, Everyone!
>> 
>> So I would also like my figures to be in physical units, instead of in my code units.  I *think* the Athena frontend doesn't read in what the unit conversions are (and I am not sure how it would do that).  Can I just do something simple like:
>> 
>> DensityUnits = 3.
>> density_physunits = grid['density'] * DensityUnits
>> 
>> Then, of course, I don't know how I would do a SlicePlot, ProjectionPlot or phaseplot in physical units...
>> 
>> Any help/advice/direction is appreciated!
>> 
>> Thanks,
>> Stephanie
> 
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