[FLASH-USERS] confused about st_energy parameter in Stir unit

[Slavin, Jonathan]

Hi,

I'm looking to use the Stir unit in a simulation using the FromFile
implementation. I've been struggling a bit with setting the input
parameters.  I think I understand most of them, but the st_energy one is
confusing me.  When I follow through the code it seems like the only
dimensional parameters used in setting the acceleration are st_aka and
st_akb which in turn are proportional to st_OUphases.  Those are
proportional to the variance used to create them which is proportional to
st_OUvar. Finally st_OUvar = sqrt(st_energy/st_decay).  So, if I've
followed that correctly the acceleration is proportional to
sqrt(st_energy/st_decay).  It seems that st_decay has units of time (s),
and acceleration should of course have units of distance/time**2 (cm/s**2),
which leads to st_energy having units cm^2/s^3, which seems odd to me. I
can see dividing out the mass, which leaves cm^2/s^2, but the extra s
dimension is strange. Should st_energy be interpreted as power per unit
mass added by stirring?

Regards,
Jon
-- 
Jonathan D. Slavin
Astrophysicist - High Energy Astrophysics Division
Center for Astrophysics | Harvard & Smithsonian
Office: (617) 496-7981 | Cell: (781) 363-0035
60 Garden Street | MS 83 | Cambridge, MA 02138
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