3D Hybrid particle-in-cell

[david]

Hello!

Currently I'm simulate the plasma cloud expansion using my 3D hybrid
PIC code.

Model description and some results of my code are available at
http://comphys.narod.ru/3d_cloud_v3.htm.

The simulation results are reasonable in general.
But some contraversal results http://comphys.narod.ru/m20d14.htm
turn out in case of the Ma > 10/
Especially suspicious things occur on a equatorial plane:
http://comphys.narod.ru/m20d14.htm#CloudVelocityXY
http://comphys.narod.ru/m20d14.htm#MF_XY
where the spatial anisotropy of cloud expansion is observed

Couldn't you help me to understand the reasons of such discrete
anisotropy?