My initial thought was that was two particles that are infinitesimally close at the start of the simulation will have radically different reflections and paths when they hit the fractal, since the fractal has no local similarity, therefore the choice of the number of particles to use in the simulation will greatly affect the shape of the reflected wave. However by the same logic that the fractal has no local similarity we can also conclude that because the fractal has no derivative, and therefore no tangent, and therefore no way to calculate the reflection angle for any point at all.