Properties of diffusive random walks in bounded domains

Properties of constant-speed diffusive random walks starting from a random point inside a bounded domain are presented. Average quantities, such as the mean length of the trajectory (or first exit time), are expressed only according to the moments of trajectories starting on the surface's body. The derivation is based on the one-velocity linearized Boltzmann transport equation. Furthermore, we generalize to the case of nohomogeneous diffusive media some relations, established before in the literature, for purely absorbing media.