Date of Award

5-10-2018

Degree Type

Thesis

Degree Name

M.A.Sc.

Department

Mechanical, Automotive, and Materials Engineering

First Advisor

Balachandar, Ram

Second Advisor

Barron, Ronald

Keywords

CFFJ, CFWJ, IDDES, Penetration length, Wall Jet, Width of recirculation region

Rights

CC-BY-NC-ND

Abstract

Counter-flowing wall jets are used as mixing devices in several industrial engineering applications, for instance; mixing of effluents in rivers, enhancement of the heat transfer from the walls, etc. Although some experimental and numerical studies have been carried out to analyze the characteristics of counter-flowing wall jets, the internal turbulence structure is yet to be understood. An analysis of the dynamics of the turbulent structures would aid in the characterization of turbulent dissipation in the counter-flowing wall jet flow field. In this study, a counter-flowing wall jet issuing into a main flow is numerically investigated using a three-dimensional, unsteady, Improved Delayed Detached Eddy Simulation for a velocity ratio (jet to main flow) of 5:1. The results of the simulation are validated with available experimental data and are presented with pertinent discussions. The interaction of the jet with the wall and the main flow results in the oscillation of the stagnation point and generates significant turbulence. The feedback mechanism between the stagnation region and the shear layer of the counter-flowing wall jet is analysed by examining the instantaneous flow field. To describe the internal structure of turbulence, the coherent structures within the flow are identified using a vortex identification criterion. These structures are also quantitatively evaluated using proper orthogonal decomposition (POD). The dynamics of the organized structures reveal the complexity of the turbulence in the counter-flowing wall jet flow field.

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