Month: August 2018

Fluid dynamics of peloton formation

by Shane, posted in Get involved, Honours/Masters projects

In competitive cycling, a “peloton” is a group of riders that travels together in formation in order to reduce drag and save energy. The shape of the peloton will change depending on headwind and sidewind and the strategy of individual riders or teams of riders.

In this project, we will study the fluid dynamics of cycling pelotons and investigate how collective behavior of cyclists can lead to peloton formation under different scenarios. No fluid dynamics knowledge is required, but Python programming experience is essential.

This project is jointly supervised by Dr Shane Keating (UNSW Sydney) and Dr Geoff Vasil (U. Sydney). Please contact s.keating@unsw.edu.au for more information.

Submit your application by Oct 26 2018 for commencement in Term 1, 2019.

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Geoffrey Vasil

by Shane, posted in Contributors

Geoff Vasil is a Senior Lecturer in the School of Mathematics and Statistics at the University of Sydney. His main research interests are the area of nonlinear dynamics of astrophysical and geophysical fluid systems. Geoff completed his PhD research at the University of Colorado at Boulder, USA in 2008 and was a postdoctoral researcher at the Canadian Institute for Theoretical Astrophysics in Toronto, Canada before joining the faculty of the University of Sydney.

One of Geoff’s specific projects is working toward a better understanding of the how the Sun manufactures global magnetic fields on an eleven-year cycle. Also, Geoff is interested in many of the basic ingredients that make up systems like the Sun. To this end, he is actively working on understanding the fundamental laws of heat transport in turbulent convection systems. He has made fundamental progress in understanding the mechanism of baroclinic instability in the presence of convection. This will have a number of consequences for understanding the dynamics of the atmospheres of the giant planets such as Jupiter and Saturn, as well as accretion disks.

Geoff also is interested in the difficult computational aspect that accompany many problems in astrophysics and geophysics. He is continuing work on modeling systems with extreme disparities in timescales, both analytically and numerically. He is one of the founding developers of the Dedalus Project, an open-source MPI-parallelized python library to solve partial differential equations, in particular those that arise in the field of fluid dynamics.

Personal website
Dedalus Project
University of Sydney School of Mathematics and Statistics

Dedalus workshop at ANU

by Shane, posted in Latest news, Workshop

Join us in Canberra this Fri Aug 24 for a special workshop on Dedalus, an open-source spectral PDE solver for Python.

Dedalus is a flexible framework for spectrally solving differential equations. Although it was developed for use in fluid dynamics research, Dedalus can be applied to any initial-value, boundary-value, and eigenvalue problems involving nearly arbitrary equations sets. You build a spectrally-representable domain, symbolically specify equations and boundary conditions, select a numerical solver, and go.

 

The workshop will be held at ANU’s Research School for Earth Science, and will begin with a seminar by Dedalus developer Dr Geoffrey Vallis (U. Sydney), followed by a hands-on workshop.

For more details please contact Taimoor Sohail.

When: Friday 24th August 2018, 1-3pm

Where: Hales Room, Jaeger 7, ANU Research School for Earth Science.

About the main image: Simulation of 2D flow over a wing-shaped obstacle with moderate Reynolds number (Re ~ 100). The flow is visualised by advecting a passive tracer concentration field; released from a perpetual localised source on the left-side of the domain. The wing is implemented with a volume-penalised immersed boundary method. Credit: Eric Hestor (U. Sydney).

To watch a movie of this and other examples, visit the Dedalus Project Vimeo page.

Summer research opportunities

by jandavidzika, posted in Get involved, Latest news, Uncategorized, Undergraduates

A number of Mathematics for Planet Earth related projects are available for summer research schemes with UNSW’s School of Maths and Stats and the Climate Extremes ARC Centre of Excellence.

These are great opportunities for domestic and international researchers to get a taste of research. Typically they are ideal for students with strong mathematical backgrounds (maths, physics, engineering majors etc) to get exposed to planet earth related topics.

The following projects are specifically proposed by Mathematics for Planet Earth contributors:

Mathematics and Statistics

Project Title: Distilling the ocean’s role in climate using phase diagrams. Supervisor(s):  Dr Jan Zika

Project Title: Lagrangian pathways and the asymmetry of the ocean’s thermohaline circulation Supervisor(s):  Dr Jan Zika

Project Title: How important are two different options for calculating specific volume in the ocean? Supervisor(s): Prof Trevor McDougall

Climate Extremes

Project Title: Pushing the ocean to extremes. Supervisor(s):  Drs Ryan Holmes and Jan Zika

Project Title: Why does the ocean look like an octopus. Supervisor(s):  Drs Jan Zika and Ryan Holmes

For complete lists of projects and details on how to apply see:

https://www.scholarships.unsw.edu.au/science-vacation-research-scholarship-ugvc1056-20182019-research-projects

https://climateextremes.org.au/2018-2019-summer-scholarships/

M4PE Seminar: August 27th, Bishakdhatta Gayen (ANU)

by Shane, posted in Climate, Latest news, M4PE Seminar, Oceans, Uncategorized

ARC Future Fellow Dr Bishak Gayen (ANU) will discuss his research in the M4PE seminar at UNSW Sydney on Monday 27 August 2018.

Title: Spanning 10 billion scales from millimetre turbulence to global circulation

Speaker: Bishakhdatta Gayen (Australian National University)

Date & Time: 4pm, Monday 27 August 2018. (Seminar will be followed by refreshments.)

Location: Red Centre room RC-3085, School of Mathematics and Statistics, UNSW Sydney

Abstract: The general ocean circulation, of crucial importance to the global climate, involves fluid motion on scales ranging from turbulence, internal waves, eddies and fronts, planetary Rossby waves and basin-scale gyre recirculation. Equilibrium is maintained between continuous large-scale forcing and energy dissipation. Understanding the physics of various dissipation mechanisms is important for improving the dynamical description of large-scale circulation. Large-scale ocean models do not accurately model turbulent convection, breaking waves, and turbulence, providing motivation to develop a better understanding of these mechanisms. In this presentation, my primary focus will be on understanding the role of turbulence and convection in ocean circulation.

In order to examine the effect of convection in ocean circulation, we have developed a model of circulation with flow driven by surface buoyancy in a closed basin using Direct Numerical Simulations. The circulation cell involves a horizontal boundary flow, turbulent plume motion and week interior return flow. We show that under planetary rotation, even in the absence of wind stress, the flow becomes three-dimensional with small-scale deep convection and broad basin-scale gyres. For the first time, DNS is used to model this circulation and quantify the heat transfer and flow energetics, demonstrating several dynamical regimes. I will also discuss the role of turbulent convection in melting of basal ice shelves and circulation around the Antarctic basin.

About the speaker: Dr Bishakhdatta Gayen is a Research Fellow at the Research School of Earth Sciences at Australian National University. His current research interests are nonlinear internal waves in the ocean, turbulent convection, modeling of Antarctic ice melting and Southern ocean dynamics. Bishak is a 2018 ARC Future Fellow, and has previously been awarded a 2013 ARC DECRA Fellowship. He has also received the RJL Hawke post-doctoral fellowship from the Australian Antarctic Science Program to study subsurface melting of ice shelves around Antarctica with implications for future sea-level rise.

About the main image: A snapshot from simulation of circulation in a closed ocean basin forced by imposed constant temperature having a variation with latitude, showing the kinetic energy on a horizontal plane near the upper boundary, temperature contours on a vertical section near the western boundary and vertical velocity on a vertical section near the northern boundary. Time averaged near-surface transport streamfunction is shown above.