Karma model. 1D pulse alternation and stopping

M nb ε Δt Δx D speed

Ymin Ymax delay it fps
This script uses simple explicit algorithm. It makes it time steps per frame.

1D excitation pulse propagation on a ring with the length L = 512×Δx.
For Δx = 0.9 after relaxation transient the pulse is (almost) stationary.
For Δx = 0.6 the pulse shape and speed are unstable and alternate.
The pulse can not propagate on a small ring. For Δx < 0.5 it stops and disappears.
We will see next that this instability leads to spiral waves breakup.

Heart rhythms     updated 3 Jan 2012