Mechanism of Vortices Appearance in the Taylor-Couette Flow System

Document Type : Regular Article

Authors

1 Laboratory of Fluid Mechanics, Military Polytechnical school, Bordj El Bahri, 16046 Alger. Algeria

2 Laboratory of Thermodynamics and Energetic Systems, USTHB, Bp 32 El-Alia, Alger, 16111, Algeria

Abstract

This work is devoted to study the Taylor-Couette flow at the early structuring stages. It is aimed to gain insight on the Taylor and Ekman vortices genesis mechanism since the first hints of presence detected at Ta=10-4. Simulations are carried out using Ansys Fluent software package. The basic system geometry is characterized bya height H= 150mm, ratio of inner to outer cylinder radii η= 0.9, radial gap δ= 0.11 and an aspect ratio corresponding to system height reported togap length, Г= H/δ = 15. Ekman and Taylor cells are tackled since the Taylor number Ta=10-4 to the first (TVF) and second (WVF) instabilities settlement at Tac1= 43.8 and Tac2= 54, respectively. It is sought to shed light on the underlying mechanism responsible for flow genesis and to identify all the intermediate successive steps from ex-nihilo when the system is at rest up to complete vortices formation. The obtained results show that presence of Ekman cells is already perceptible since a Taylor number as low as Ta= 10-4. In fact, localized overpressure zones are detected on system inner endcaps surfaces regularly distributed according to a π/2 phase lag. These overpressure zones azimuthally propagate to meet and cover the entire gap circumference when Ta~10-2 to10-1.

Keywords


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Volume 15, Issue 1 - Serial Number 63
January and February 2022
Pages 129-137
  • Received: 08 February 2021
  • Revised: 01 August 2021
  • Accepted: 09 August 2021
  • First Publish Date: 14 November 2021