Gravity Control

by streeter — last modified 2007-03-30 02:59

Namelist GRVCON
Parameter	Data Type	Attribute	Valid Values	Notes
guniv	Real	Gravitional Constant	6.67e-8 (cgs)	See GRVCON_Remarks(1)
tgrav	Real	Time at which to enable gravity	User's Choice (sec)	See GRVCON_Remarks(2)
ptmass	Real	Mass of imposed point mass	User's Choice (gm)	See GRVCON_Remarks(3)
x1ptm	Real	1-coordinate of point mass	User's Choice (cm)
x2ptm	Real	2-coordinate of point mass	User's Choice (cm)
x3ptm	Real	3-coordinate of point mass	User's Choice (cm)
XWEDGE	Logical	Compute M(r) assuming a 45 degree wedge	.TRUE. or .FALSE.	See GRVCON_Remarks(4)
GSUP	Integer	Cycle number at which to compute gravity	User's Choice (cm)	Obsolete; not used.

While ordinarily one would wish to set GUNIV to the usual CGS value; the pressureless-collapse test problem actually assumes that G = 1. GUNIV was therefore included in the input namelist for problem flexibility.
TGRAV allows the user to delay the calculation of gravity until some amount of evolution time has passed. Evidently there was some test or application where this was useful. Perhaps you'll find it useful.
If XPTMASS = .TRUE. in namelist PHYSCON, then PTMASS provides the mass in grams of the point mass to be included. X(1,2,3)PTM provide the coordinates of the point mass in the computational domain.
If XSPHGRV = .TRUE. in namelist PHYSCON, then set XWEDGE = .TRUE. if the angular grid is an equatorial wedge spanning 45 degrees. This enables a correct computation of interior mass vs radius. If the angular mesh spans a full 180 degrees, set this flag to .FALSE. (default).

November 2009

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