Condition for the Incipient Motion of Non-Cohesive Particles Due to Laminar Flows of Power-Law Fluids in Closed Conduits

Aldo Tamburrino,Cristóbal Traslaviña

doi:10.3390/w12051295

Abstract

The results of an experimental study on the condition of incipient transport of non-cohesive particles due to the flow of a power-law fluid in a rectangular pipe are presented in this article. The pipe can change its inclination, and experiments were carried out with positive and negative slopes. From a dimensional analysis, the parameters that define the condition of incipient motion were found and validated with experimental data. Thus, the threshold condition is well defined by a particle Reynolds number and a Galileo number, properly modified to take into account the power-law rheology of the fluid. The experimental data are also presented in a standard Shields diagram, including the data obtained in other studies carried out in open-channel laminar flows of Newtonian and power-law fluids.

Highlights

Introduction and ObjectiveThe flow of non-Newtonian fluids over non-cohesive granular beds can be found as much in industry as in nature [1,2,3]
In order to have a clearer image of the data corresponding to incipient motion, only the points associated to this condition are shown in Figure 4, including the best fitting curve, which is given by Re∗ = 0.434Ga . , with a correlation coefficient R = 0.97185
In order to have a clearer image of the data corresponding to incipient motion, only the points associated to this condition are shown in Figure 4, including the best fitting curve, which is given by Reynolds number (Re∗)p = 0.434GaK 0.504, with a correlation coefficient R2 = 0.97185

Summary

Introduction

The flow of non-Newtonian fluids over non-cohesive granular beds can be found as much in industry as in nature [1,2,3]. Under certain non-desirable operating conditions, the flow velocity can decrease, and larger particles of the slurry settle. The mixture formed by the finer, non-settling particles and the carrying fluid (water) behaves as an equivalent non-Newtonian fluid that can be modeled as power-law (or Ostwald–de Waele) fluid [5]. Once the deposit is generated, it needs to be removed by the flow In this context, the goal of this article is to present the results of an experimental study aiming to define the condition of incipient motion at which the particles start to move, due to the action of a laminar flow of a power law fluid. The fluid mimics the rheology of the mixture of water and fine sediments of the slurry

Objectives

Results

Discussion

Conclusion