Laminar, Transitional and Turbulent Motion of Fruit Purees Within Circular Pipes

Abstract

The results of an experimental investigation aimed to study both the rheological and fluid dynamic behaviour of two kinds of fruit purees at different pulp concentrations are presented in this work. An experimental setup based on the rectilinear pipe viscometer principle was used for a preliminary rheological investigation of the analyzed products. By applying either the classical Rabinowitsch and Mooney or the recent Thikonov method of regularization of integral equations, these products could reliably be considered as purely-viscous time-independent fluids. The laminar motion was described by means of the well known Metzner and Reed method while the corresponding resistance laws for turbulent motion were modeled by using the Dodge and Metzner method. The comparison of the point onset of turbulence against the ones obtained by means of the Mishra and Thripati and Hanks formulas would, however, suggest that in transitional regime the viscoelastic effects could have non-negligible influence on the dynamics.