Meeting Update -- 11/4/13 -- Erica

Working on readings and colliding flows simulations. I first ran a quick and dirty simulation with MHD on, and extrapolating BCs to reproduce the striations Jonathan talked about earlier.

MHD COLLIDING FLOWS:

Here are some movies,

normal slice (y-z plane is normal to flow direction) of the density and Bx-

​http://www.pas.rochester.edu/~erica/normal_slice_BandRho.gif

parallel slice(y-z plane is normal to flow direction) of the density and Bx-

​http://www.pas.rochester.edu/~erica/parallel_slice_BandRho.gif

here is positive vx on a log scale, both types of slice -

​http://www.pas.rochester.edu/~erica/sliced_vx.gif

The large shock feature that blows backward off of the collision region jumps out at me. The sound speed is initially Cs = 117 everywhere for the 0th frame. Dt = 0.01. So the farthest a sound wave should have been able to travel is ~1 by the 1st frame. What is causing this blow off?? — This is wrong I think, because I didn't take B into account in the sound speed. . .

here is a normal slice of pressure -

​http://www.pas.rochester.edu/~erica/normal_slice_press.gif

HYDRO COLLIDING FLOWS:

normal slice of rho-

​http://www.pas.rochester.edu/~erica/normal_slice_rho.gif

vx -

​http://www.pas.rochester.edu/~erica/normal_slice_vx_hydroCF.gif

press-

​http://www.pas.rochester.edu/~erica/normal_slice_press_hydroCF.gif

to see that the striations are absent in the hydro set-up, see this parallel slice of vx -

​http://www.pas.rochester.edu/~erica/parallel_slice_vx_hydroCF.gif

For the hydro case, dt = .8, scalegrav = .02, Cs = 90. The Jeans refinement is lambdaj = 4dx, solving for rho gives - (Cs/(4dx))2(pi/G) ~ 100,000 (increase of more than 5 orders of magnitude) before a sink can form…

Comments

1. Erica Kaminski -- 11 years ago

I learned that the Jeans length calculation is not exactly correct, given the idea with cooling is that the overdensities that form will cool, making the jeans length smaller, and thus, a sink particle should form more readily than this calculation predicts..