Prevailing Conditions of Flow in Particulate Systems

This chapter reviews the main prevailing features of flow in particulate systems. The flow behaviour of a powder is a function of different parameters and conditions, such as the particle properties, applied stresses, flow regime, environmental conditions, and time. The differences and similarities of bulk materials and liquids in terms of stress distribution are discussed, and the main mathematical models for estimation of these stresses are mentioned briefly. This chapter also discusses the relation between stress and strain rate in different powder flow regimes, such as the static, quasi-static, intermediate, and rapid granular regimes. The flow behaviour of powder alters with changes in environmental conditions, such as the temperature, relative humidity, and electrostatic charging, all of which are discussed here.