The following steps will be needed to modify VH-1 to run
a supersonic jet.
Boundary Conditions (set in init.f)
Lower boundary is totally reflecting (nlefty = 0)
Upper boundary is flow through (nrighty = 1)
Right boundary is flow through (nrightx = 1)
Left boundary is reflecting (nleftx = 0)
if R > Rjet, fixed inflow (nleftx = 2)
if R < Rjet. This switch will have to be made within the
sweepx.f subroutine since different rows will need different
boundary conditions, e.g.,
if(j.lt.jjet) then
nleftx = 2
else
nleftx = 0
endif
The variable jjet must be set somewhere, and put in global.h
so that other subroutines know its value. jjet should be at least
10, 20 would be even better.
Geometry: 2D Cylindrical (ngeomx = 0, ngeomy = 1)
Initial Conditions: The numerical grid will be initialized with
a uniform density and pressure, and zero velocity.
Since the density in an adiabatic jet model is just a scale factor, we
can choose any value (say, 1!). While we're at it, lets set the
pressure to be 1 also.
Jet Inflow: the values of dinflo, pinflo, einflo, uinflo,
and vinflo must be set in init.f for the values of the input jet stream.
These values will be used to set the boundary conditions when nleftx = 2.
Let's assume the pressure in the jet is the same as the ambient medium
(1). The density can be anything, but let's keep it close to the density
in the ambient medium (say between .1 and 10). A jet with density = 10
will move across the grid very fast (high momentum flux), a jet with
density = 0.1 will move across the grid very slowly. The velocity
should be supersonic, say a Mach number of 10.
Grid Size: The grid size (ii,jj) and (imax,jmax) should
be as long (ii) as you want the jet to be, and at least 5*jjet wide (jj).
