An experimental investigation of capsules of anomalous shape conveyed by liquid in a pipe

Abstract

This paper deals with the effect of bulk fluid velocity, diameter and length ratios, apparent density and volumetric concentration on the capsule/liquid velocity ratio, pressure gradient of the capsule flow in the pipe and on the position of capsules. The position and shape deformation of semi-rigid capsules contributed to the explanation of the effect and distribution of the transversal hydrodynamic forces, acting on a capsule. Measurements were carried out in a horizontal straight plexiglass pipe of inner diameter 0.05 m and water was used as a carrier liquid. It was found that the semi-rigid capsule trains reached lower velocities than the rigid ones for the regime given by Reynolds number ( Re) lower than 5×10 4, whereas the opposite holds for the region where the Re exceeds 10 5. The semi-rigid capsule trains have about 20% lower pressure gradient than trains consisted of identical solid cylindrical capsules for the regime given by Re lower than 5×10 4, for the higher flow velocity this effect gradually disappears.