shockwave simulation

Lammps users,

I'm trying to simulate shockwave simulation in metals. I followed
steve suggestion and right now i'm using the " wall/piston" feature .
Basically i construct a Bulk crystal , then i define periodic boundary
conditions at the x y directions and "shrink-wrapped" in z-direction,
the piston is place at the left edge i.e "fix walls all wall/piston
zlo pos 0.0 0.0 0.0 vel 0.0 0.0 0.0 units box" and it remains fixed
(at rest), then the unshocked target material is given an initial
velocity of -up e.g "velocity atom_box set 0 0 -9.45" if i'm correct
this will produce a shock wave that moves out from the stationary
piston face at velocity "us".

My question is the following : how can i find the velocity of the
shockwave "us" ? . I'm guessing that "fix piston" reflect the velocity
of the particle "up" i.e if a particle hit the piston wall , then its
velocity its flipped " , then the shockwave propagate at a velocity
"up" ? .

Any advice would be greatly appreciated
Oscar G.

Shock waves in a material can move faster or
slower than the impulse that produced them.
To track the wave in the material you typically need
to do viz and/or compute some kind of disorder
parameter, like compute cna/atom or centro/atom.


You can also look at "Budzien, Thompson and Zybin, JPC B 113, 13142 2009",
in which they defined the shock front by monitoring the change of
temperature, density and disorder wrt time, which in turn converts to the
shock velocity.