2 spheres collapsing
The initial front is made of a plane of equation spheres with a radius r0 = 1 and the speed is defined by
c(x,t) = 1 -t. The final time is T=3 and the time stride is Δt = 0.1. As long as the speed is
positive the circles will propagate forward. At t=1, the speed changes of sign and the circles
start propagating backward.
This example computed with the Generalized Fast Marching Method in a 3 dimensional mesh. The initial condition is a plane defined by u0(x) = x2 + x1 - 1, and the velocity function by c(x,t) = x1. The final time is T = 1.
Van Der Pol oscillator
We compute the minimum time function to reach the target