According to the intuition by Maurice Antony Biot, the concept of Fluence can easily describe different and interdisciplinary physical phenomena. Fluence relates directly to the number of particles that cross or hit a reference surface, directly impacting the specific problem. Moreover, when related to the time, it allows describing the flux of particles through the reference area. Therefore, the physical properties which are transported by the particles can be easily associated with specific problems with an unprecedented easiness of use.
Laser beams, particles, ions beams, acoustic and fluid dynamic problems can benefit from this concept for specific and standard description. Moreover, even if referred only to the number of particles, it avoids using complex statistical methods such as the kinetic theory of the gasses.
This paper is an homage to the work of Maurice Antony Biot and shows how the Fluence concept can be helpful in the solution of multiple physical problems.