Symmetry of the Flows of Newtonian and Non-Newtonian Fluids in the Diverging and Converging Plane Channels

TL;DR

This study numerically investigates laminar flow regimes in diverging and converging channels for Newtonian and non-Newtonian fluids, analyzing flow symmetry, stability, and transitions across different Reynolds numbers.

Contribution

It provides new numerical insights into flow regime transitions and symmetry breaking in plane diffusers and confusors for various fluid types based on Reynolds number.

Findings

Flow transitions from symmetric to asymmetric regimes are identified.

Existence ranges of flow modes depend on Reynolds number and fluid type.

Flow behavior differs between Newtonian and non-Newtonian fluids in diverging/converging channels.

Abstract

The results studying various laminar flow regimes in diverging and converging plain channels (diffuser and confusor) with a small opening angle of channels (diverging and converging angles) are presented. The results are obtained for a viscous incompressible fluid by numerical simulation based on solving the Navier-Stokes equations. The paper presents the results concerning the change in the nature of flows from stationary - symmetric to stationary - asymmetric and to non-stationary in the diffuser and confusor in dependence on the Reynolds number. The ranges of existence of these flow regimes in plane diffusers and confusors depending on the Reynolds number for Newtonian, pseudo plastic and dilatants fluids with the Ostwald-de Waele power law for viscosity are numerically found. The transitions of flow regimes in the diffuser from symmetric steady state to the asymmetric one and to the asymmetric unsteady mode in dependence on the Reynolds number are shown. The values of Reynolds number that determine the existence ranges of these flow modes in the cases of Newtonian and non-Newtonian fluids are given.