Traveling fronts in systems of particles with random velocities.

We explore a reaction-dispersal mechanism for the generation of wave fronts which consists of a set of particles traveling with random velocities (chosen from arbitrary distributions) which experience an autocatalytic reaction. The differences found between this mechanism and approaches based on the continuous-time random walks, where the particles are assumed to perform discrete jumps from one position to another, are analyzed and discussed. A complete analytical treatment of our velocity model is achieved, which allows us to predict the constant speed of traveling fronts or their time dependence in case they are accelerated. Also, a general criterion to distinguish the situations of fronts with constant speed from those accelerated is provided. From it, we conclude that accelerated fronts should be expected in different situations easily achievable in nature.