Department of Mechanical Engineering, University of Auckland Seminar Series

PG Talks:Understanding turbulence through novel numerical simulations

Speaker

Dr. Michael MacDonald

Institute

Department of Mechanical Engineering, University of Canterbury

Time & Place

Tue, 26 Jan 2021 13:00:00 NZDT in E14, Engineering Core

All are welcome

Abstract

Turbulent flows are ubiquitous in engineering and geophysical applications, such as in the flow of water close to a ship's hull or of air over the Earth's surface. They are typically studied using very simple, idealised configurations, however, realistic turbulent boundary layers often have complexities which are not captured by these simple configurations. Here, I will talk about how novel numerical simulations can be used to accurately and efficiently study aspects of these realistic turbulent boundary layers. Firstly, I will talk about the effects of moisture in the context of fog, and how it grows as an internal boundary layer within the pre-existing atmospheric boundary layer. Secondly, I will discuss the effects of rough surfaces, which increase momentum and heat transfer within the turbulent boundary layer. Accurately predicting these effects of roughness is often exceedingly difficult, which makes design predictions and the examination of rough-wall flows challenging for both industry and academic research. I outline a framework termed the minimal channel in which fully resolved numerical simulations of rough-wall turbulent flows can be conducted at a much reduced cost compared to conventional direct numerical simulations (DNS). The minimal channel is then used to simulate turbulent flow over a variety of roughness geometries that would otherwise be prohibitively expensive to study.



Michael MacDonald

Biography

Michael MacDonald is a lecturer in Fluid Mechanics/Aerodynamics in the Department of Mechanical Engineering, University of Auckland. He graduated from the University of Auckland with a BE(Hons) in Engineering Science in 2012 and obtained his PhD in Mechanical Engineering from the University of Melbourne in 2017. He was then a postdoctoral scholar at the NASA Jet Propulsion Laboratory, California Institute of Technology in the Atmospheric Physics and Weather Group, before returning to Auckland in 2019. Michael's research involves using numerical simulations to study turbulent flows and how they are affected by complexities such as roughness, moisture or rotation. He aims to uncover the essential ingredients of turbulence, with an eye towards providing robust models that can be used in engineering and geophysical applications.