2D Colliding Flows

Diameter of colliding flows	25 pc
Mach	1.5
Number density	1 cm-3
Beta	1
Cells per Jeans Length	64
Amplitude of interface perturbations, scaled to largest flow diameter	.015
Time to shut off flows	30 Myr
Cooling	Modified II curve (10K at 1000/cc)
Final time	17 Myr
dt of framerate	.12 Myr
resolution	(642 x 1) + 3 levels
box size	50pc X 50pc X dx in x,y,z respectively
finest dx	0.03 pc
Boundary conditions	reflecting, and keep B-normal in x, open in y and z
self-gravity?	yes

(Note: The inputs in the data files are given above, however, visualization in Visit seems to show both of these values less by 0.5 — I have to check into this more)

Here are some stills of the initial conditions. First is the first frame (t=dt) showing the mesh,

Here is just the density at this first frame, the legend is in particles/cc:

And here is the x velocity for the 0th frame (t=0),

(Note the 0th frame for the density just shows a uniform field = 1/cc)

Here is a movie of the density, with field vectors overlaid. The field starts with a Beta=0.5 everywhere in the box. We see early on the NTSI develops and grows for the first 20 frames or so. By about 2 Myr, it seems the NTSI begins to collapse back toward the midplane. Without the troughs of the NTSI for the material to funnel toward, the material is instead splashed laterally in the y-direction. This creates large shear that excites KH modes especially at the tops and bottoms of the colliding streams. The first core (sink particle) forms late in the simulation, by 15 Myr. Peak densities are ~12,000 /cc < H2 densities.

movie​