First Advisor

Raúl Bayoán Cal

Term of Graduation

Summer 2021

Date of Publication

9-27-2021

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Mechanical Engineering

Department

Mechanical and Materials Engineering

Language

English

Subjects

Anisotropy, Turbulence, Reynolds stress, Fluid mechanics

DOI

10.15760/etd.7682

Physical Description

1 online resource (viii, 83 pages)

Abstract

With data from experiments on a jet of air emitting from an orifice flush with the floor of a wind tunnel providing a transverse flow, analysis is conducted to extract information about the state of anisotropy in the Reynolds stress tensor. Inflow velocities are modulated across two distinct turbulence intensity regimes while holding jet exit conditions constant, providing an opportunity to isolate effects of both jet to crossflow velocity ratio, r and the effects of the turbulence carried by the crossflow. Anisotropy in the Reynolds stress tensor is examined through anisotropy invariant maps and evolution of the function F, combining the two independent invariants of the normalized anisotropy tensor. A quaternion representation of the three dimensional rotations in the principle axes of the normalized anisotropy tensor is developed allowing for concise graphical representations of the eigen-matrix of the normalized anisotropy tensor. A component-wise view of the anisotropy tensor is presented showing the contributions of its individual components to the state of anisotropy. It is found that emanating into a crossflow which is itself largely anisotropic, a jet will develop a more isotropic core region as it bends over into the crossflow, this region persists beyond 10 jet diameters downstream of the exit. Some of the more isotropic turbulence diffuses beyond the commonly understood bounds of the jet and this effect is enhanced by more energetic turbulence in the crossflow.

Rights

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

Persistent Identifier

https://archives.pdx.edu/ds/psu/36596

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