5. Conclusion

This article reviews the state of the art in gravity flow of granular solids in silos. It should be noted that the term "granular solids" is used here to designate materials with a large particle size, for which gravitational forces (weight) are predominant over interparticle forces. The basic principles and definitions, as well as the elementary mechanisms involved, were first presented. Emphasis was then placed on flow regimes, stress fields (static and dynamic) and velocity profiles. For all these aspects, the available models and their reliability were discussed, along with the basic principles and assumptions on which they are based. For simple silo geometries, these models generally provide a good estimate of the parameters of interest.

Generally speaking, it is possible to distinguish two main modes of flow within silos:

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