3D MHD Shear Flows

Testing the effects of magnetic fields on shear flows.

Here are the runs' parameters:

Diameter	40 pc
Mach	1.5
Shear Angles	15, 30, 60 degrees
Density	1 cm-3
Beta	1, 10, Hydro
Initial B-field orientation	Uniform in x
Cells/Jeans Length	64
Cooling	II curve
Final time	20 Myr
Resolution	48 + 2 ~ 200 cells effective
Box size	62.5 x 75 x 75 pc in x,y,z
Boundary conditions	Extrapolating, and multipole
Self-gravity	On

Orientation of Collision Interface

Plots showing the direction of the tilted interface:

Shear15	Shear30	Shear60

Interface is rotated about y.

Evolution of the tilted interface

A slice taken through the center of the box, in the x-z plane, shows that in the strong magnetic field case, the interface tends to realign so that it is vertical in z:

movie​

Interestingly, the hydro case might also straighten out..?

Column Density Maps

These column density maps are made by summing the density over all cells through a given dimension, using both the gas and sink components. You can use the above 3D plot for orientation. In the 'down the barrel case', the vertical dimension is z, and the horizontal axis is y. The axes are given in the other plots.

'Down the Barrel'	Normal in Y	Normal in Z
movie​	movie​	movie​

A strong ring effect is present in the strong beta cases that isn't in the weaker B field and hydro case. The ripples are also interesting, not sure whether they are numerical or physical yet.

Run	Time when sink first appears	Number of sinks by end
Beta1, Shear15	Frame 160/200	8
Beta1, Shear30	Frame 173/200	7
Beta1, Shear30	No Sinks Form	0
Beta10, Shear15	Frame 184/200	5
Beta10, Shear30	Frame 161/200	2
Beta10, Shear30	Frame 196/200	1
Hydro, Shear15	Frame 118/200	6