Drag on individual cubic assemblies of spheres in non‐newtonian tube flow

Abstract

An obstacle in modeling aseptic processing of particulate foods is the lack of a reliable estimator for the drag force of the non‐Newtonian liquid phase on the suspended particles as they flow through the holding tubes of such systems. The objective was to develop an expression for the drag force on cubic assemblies of spherical particles suspended in a pseudoplastic fluid flowing in a tube. An apparatus was assembled for direct measurement of the drag force exerted by solutions of sodium carboxymethyl cellulose (CMC) on the assemblies inside a tube. An empirical drag correction factor, as a function of particle volume fraction (applicable to Stokes' law), was developed.

Drag on Multiple Sphere Assemblies Suspended in Non‐newtonian Tube Flow

“…Since the three-assembly arrangement better represents continuous flow of particulate suspensions than the single assembly situation, further analysis was performed using the drag force measurements on the three-assembly configuration only. where, particle concentration is defined as (Subramaniam and Zuritz 1994):…”

“…In a later work, Subramaniam and Zuritz (1994) studied the drag force on single cubic assemblies of spheres and, using average fluid velocity, developed the following equation for the correction factor for drag coefficient based on concentration (volume fraction): With their study, as with any other study using a single assembly of spheres, the question arises whether this type of experiment provides a true representation of the effect of particle concentration on the drag correction factor for continuous flow of a homogeneous suspension (probably better represented by the presence of similar upstream and downstream assemblies). In order to answer this question, the present study was conducted with the objective of investigating the influence of upstream and downstream assemblies on the drag force experienced by the single test assembly.…”

“…This experiment is supposed to better simulate a continuous system than the one with a single assembly of spheres. The experimental system used in both sets of experiments were the same as that used by Subramaniam and Zuritz (1994).…”

Comment on “drag on individual cubic assemblies of spheres in non‐newtonian tube flow”, Girish Subramanian and Carlos A. Zuritz, Can. J. Chem. Eng. 72, 201–206 (1994)

“…In a recent article in this journal, Subramaniam and Zuritz (1994) have reported experimental results on the drag on cubic assemblages of solid spheres in power law fluids. No such other results are available in the literature, as noted by Subramaniam and Zuritz (1994).…”

“…In a recent article in this journal, Subramaniam and Zuritz (1994) have reported experimental results on the drag on cubic assemblages of solid spheres in power law fluids. No such other results are available in the literature, as noted by Subramaniam and Zuritz (1994). The experimental results have also been compared with the predictions of Zick and Homsy (1982) for the flow of Newtonian fluids past cubic arrays and, not surprisingly, the correspondence is found to be rather unsatisfactory.…”