Background

Air–water flows can be found both in nature and in water infrastructure. In large hydraulic structures, such as dams, air can be entrained continuously along a spillway or as a free-falling jet, as well as locally in the plunge pool or in the downstream energy dissipator. Flows are composed of a mixture of turbulent waves, bubbles, droplets, and spray, encompassing a wide range of length scales, from centimeters down to sub-millimeter scales. Flow aeration is a key feature and must be taken into consideration when designing a hydraulic structure, which is due to cavitation protection, drag reduction, and flow bulking. While these effects have been investigated in the past, mostly empirical relationships are used in hydraulic design, while some underlying physical aspects remain unexplained.

Problem statement and research objectives

Air–water flows can occur in large hydraulic structures during extreme flow events. Considering the effects of self-aeration in hydraulic design is of utmost importance to ensure safe operation under challenging conditions. Currently, the depth and breadth in the description and modelling of air–water flows are far from that in non-aerated, monophase flows. Whereas the flow aeration is an essential feature of flows across hydraulic structures, it still remains tedious to measure and uncertain to model. The candidate will work on the frontiers of knowledge on self-aerated flows using a brand-new tilting flume facility, established at UNSW Canberra. The following research objectives are proposed as indicative starting point for further discussions:

- Explore experimental options for the measurement of air-water flows

- Evaluate interfacial velocity profiles and comparison to well-known profiles in monophase boundary layers

- Develop models to predict the behavior of self-aerated flows

Some representative publications on this topic from our research group are available here:

Linking turbulent waves and bubble diffusion in self-aerated open-channel flows: two-state air concentration

Turbulent free-surface in self-aerated flows: superposition of entrapped and entrained air

Developing the next generation of dual-tip phase-detection probes for air-water flow experiments

Air–water flows

Your profile

You have a BSc or BEng Honours degree or equivalent (GPA >= 85%) in Civil or Environmental Engineering, with a research interest in fluid mechanics. You are motivated and enthusiastic about working on the interface between fundamental and applied research. You have the ability to work independently and as a member of a research team, while demonstrating a collaborative attitude. You are able to review and engage with interdisciplinary studies and are driven by curiosity. You have excellent analytical skills and communication skills, written as well as spoken. English language proficiency is important.

For more information, send your CV and transcripts to [email protected]