Research Seminars 2016

Date

Time & Venue

Speaker(S)

Topic

26/08/2016

12-1pm


Civil Engineering Lecture
 Room 1

Prof Kenny Kwok

Western Sydney University

The role of wind-structure interaction on air ventilation and air quality in urban environment

09/09/2016

Dr Murali Krishna Talluru
The University of Sydney

Dispersion of a scalar quantity in a turbulent boundary layer

23/09/2016

Ms Fiona Tang
The University of Sydney

Microbiological modulation of suspended particulate matter dynamics

07/10/2016

Dr Joshua Yen
The University of Sydney

Laser-Induced Fluorescence & Particle Image Velocimetry of natural convection flows in differentially heated cavities

21/10/2016

Mr Daniele la Cecilia
The University of Sydney

Ecological risk assessment: a case study of atrazine biodegradation in soil

Ms Thu Ha Nguyen
The University of Sydney

Methods for sediment-attached biomass measurement

04/11/2016

Dr Jingping Wu
The University of Sydney

Schlieren measurement of temperature in thermal boundary layers

08/11/2016 

Dr Edoardo Daly

Monash University, Melbourne

Hydrology of ephemeral catchments:observations and modelling

18/11/2016

A/Prof Liping Yao
Southwest University, China

Thermocapillary flow in a liquid bridge

Mr Harrison Jones &
Ms Pearl
  Elgindy
The University of Sydney

Performance of a solar chimney with a dual-cavity system

02/12/2016

Mr Abolghasem Naghib
The University of Sydney

Natural convection induced by radiation


All are welcome to attend and/or present!

Please direct enquiry to A/Prof Chengwang Lei.
Tel: (02) 9351 2457, Email: Chengwang.Lei@sydney.edu.au


The role of wind-structure interaction on air ventilation and air quality in urban environment


Prof Kenny Kwok - Friday 26 August 2016

Abstract
The quality of Indoor and outdoor air have a significant impact on the health and well-being of the general population. The recent trend toward urban living and the dramatic increase in high-rise residential building construction to meet this growing demand heighten our awareness of the impact of high-density high-rise building development on air ventilation and dispersion of air-borne pollutants. Evidently building arrays in close proximity and deep street canyons adversely affect pedestrian level air circulation, air ventilation within the urban fabric, and dispersion of air pollutants. This seminar presents the results of investigations on air ventilation and air pollutant dispersion around high-rise buildings using wind tunnel model studies and CFD simulations. The results show that air ventilation and air pollutant dispersion around buildings are dominated by wind-structure interaction, with building shape, building grouping and separation, and podium structure also playing a significant role.

Short Biography
Professor Kenny Kwok is a Professor of Engineering at Western Sydney University. His research interests include wind engineering, structural dynamics, vibration control, human perception of motion, and environmental fluid mechanics. His research focuses on fundamental aspects of building aerodynamics and wind-structure-occupant-damper interactions, and their practical applications to real life situations. He has published over 500 articles in journals, book chapters, invited and keynote papers, and conference papers. He is currently the lead Chief Investigator of two Australian Research Council Discovery Projects, one to study the effects of motion-induced sopite syndrome on occupant well-being and work performance in wind-excited tall buildings, and one to investigate bushfire-enhanced wind and the wind load effects on buildings. He is a Life Member of the Australasian Wind Engineering Society and a Fellow of the Hong Kong Institution of Engineers and Institution of Engineers, Australia. He is Chairman of ASCE/SEI Subcommittee on Human Perception of Motion and a member of Standards Australia Technical Committee BD-006-02 Wind Actions.


Dispersion of a scalar quantity in a turbulent boundary layer

Dr Murali Krishna Talluru - Friday 9 September 2016

Abstract
Environmental concerns due to the spread of urban areas is increasingly demanding a better prediction of hazardous gases released from a ground level or an elevated source in the atmospheric boundary layer. This requires proper understanding of (i) turbulent boundary layers over urban areas and (ii) the mechanisms of scalar dispersion. In the last decade or so, there has been tremendous developments towards understanding the structure of a turbulent boundary layer and here, we use that knowledge to study the interaction between a gas plume and a turbulent boundary layer. To this end, simultaneous measurements of velocity and concentration are carried out in the boundary layer wind tunnel at the University of Sydney. Statistics of velocity and concentration will be presented with a particular focus on how the plume spread in the vertical direction. Further results on probability distributions of velocity and concentration will be discussed

Short Biography
Murali Krishna Talluru is a post-doctoral research fellow in the school of Civil Engineering and is currently working with Dr Kapil Chauhan on the topic of dispersion of pollutants in atmospheric boundary layer. He obtained Bachelor’s degree in Mechanical Engineering in 2007 from the Indian institute of Technology, New Delhi, India. Between 2007-2009, he worked as a school teacher and then as a technical manager at Unilever, India. Krishna moved to Australia in 2009 and obtained his PhD in 2014 from the University of Melbourne. During his PhD, he investigated turbulent boundary layers on smooth surfaces and implemented both passive and active flow control techniques to reduce aerodynamic drag. Later, he worked as a Research Associate at the University of Newcastle, where he studied different types of turbulent flows, such as jets, wakes, grid turbulence and rough wall boundary layers. After moving to Sydney University, he has been actively involved in many wind engineering projects related to pedestrian comfort, cladding pressure and structural loading with industry clients like Aurecon, SLR and GWTS. His other areas of expertise include, experimental techniques, environmental fluid mechanics, drag reduction and shear flows


Microbiological modulation of suspended particulate matter dynamics

Fiona Tang - Friday 23 September 2016

Abstract
The study of suspended particulate matter (SPM) dynamics has conventionally focused on physical and hydrodynamic interactions, with little attention paid on exploring the role of SPM as a micro-ecosystem that sustains a wide diversity of microbial colonies. This project puts forth a new paradigm of SPM dynamics that integrates mineral, chemical, and biological components into one framework to emphasis the role of microorganisms in altering the chemistry and structure of SPM, which further affect its transport and deposition. Microbiological modulation of SPM dynamics was investigated in this project by coupling experiments with numerical models. In this seminar, I will focus on the experimental aspects of this project. First, I will introduce the experimental facility and techniques that were developed for use in this project. Next, some key findings from experiments will be presented. Finally, I will close the presentation by giving an overall vision and perspective on this project.

Short Biography
Fiona is a PhD candidate at the School of Civil Engineering, The University of Sydney, working with Dr. Federico Maggi. Her research interest lies in subjects related to water resources management, coastal and river engineering, sediment dynamics, sediment and water quality, hydrology, aquatic biogeochemistry, and ecological functions. She is interested in both experimental- and modelling-based research.


Laser-Induced Fluorescence & Particle Image Velocimetry of Natural Convection Flows in Differentially Heated Cavities

Dr Joshua Yen - Friday 7th October 2016

Abstract
Natural convection is an important heat and mass transfer process that occurs on a wide range of scales; from geophysical and oceanic flows down to the cooling of microelectronics. Simultaneous, whole-field and non-intrusive velocity and temperature measurements are highly desirable for such flows as they allow for, in addition to the primitive field variables, other important quantities like heat transfer rate and turbulent heat flux to be computed, and also form the basis for determining more complex quantities such as entropy production. This seminar presents the latest work undertaken at the Centre for Wind, Waves and Water on simultaneous velocity and temperature measurements using particle image velocimetry and laser-induced fluorescence for the natural convection flow induced in a differentially heated cavity. Evolution of the velocity and temperature fields will be presented, and challenges encountered in our testing of this concurrent measurement technique will be discussed.

Short Biography
Joshua is a post-doctoral research associate at the School of Civil Engineering with research interests in the areas of unsteady separation, flow control, vorticity dynamics, natural convection and wind engineering. He obtained his Bachelor’s Degree and PhD in Aerospace Engineering in 2010 and 2015 from the University of New South Wales. During his PhD, he investigated the phenomenon of dynamic stall on helicopter and wind turbine rotor blades and its control using synthetic jets. Joshua moved to the University of Sydney at the end of 2015 to work with A/Prof Chengwang Lei and Prof John Patterson on the topic of natural convection. He is the Student Lead on the Young Engineers & Students Technical Sub-Committee for the 17th Australian International Aerospace Congress.


Ecological risk assessment: a case study of atrazine biodegradation in soil

Mr Daniele la Cecilia - Friday 21st October 2016

Abstract
Agrochemicals are essential to support crop yield in modern agriculture. In the last 50 years, herbicides have represented the greatest share among those agricultural chemicals. Despite herbicides may have some advantages, it has also been acknowledged that they can pose a risk to non-target organisms Not only the use of herbicides may have direct negative impacts on the flora and fauna inhabiting the environment, but also they may disrupt the beneficial services that ecosystem used to provide. For instance, nitrifying bacteria are essential as they convert ammonium to nitrate, which is more easily uptaken by plants as the nitrogen source, but their activity may be inhibited by toxic level of herbicides in soil. Therefore, in an attempt to shift towards a more sustainable agriculture, predictive tools capable to anticipate the biological processes and interactions between soil, plant, and microbial soil populations should be integrated to predict pollutant concentrations and their persistence in soil as a result of current crop management practices. In this seminar, I will present the Michaelis-Menten-Monod kinetic equations, which are used to describe the dynamics of a substrate as subjected to chemical and biological degradation activity, and how the corresponding biological parameters can be derived. As an example to this approach, the dynamics of atrazine biodecomposers is presented and a sensitivity analysis of various initial substrate and microbial biomass concentrations will highlight the importance of those biological processes in reducing soil contamination by agrochemicals.

Short Biography
Daniele la Cecilia is a PhD student at the School of Civil Engineering, The University of Sydney, under the supervision of Dr. Federico Maggi. After graduating from the University of Trento, Italy, and before starting his PhD career, Daniela worked at the Institute for Alpine Environment, EURAC, Bolzano, Italy. Currently, his research focuses on soil biodegradation of agricultural chemicals. Other research interests are soil biogeochemistry, ecohydrology, and agroecology.


Methods for sediment-attached biomass measurement

Ms Thu Ha Nguyen - Friday 21st October 2016

Abstract
The direct measurements of biomass using microscope cell counting and flow cytometry face many disadvantages when sediment particles are involved. On the other hand, indirect measurements that involve conversion factors from total organic carbon, chlorophyll and fatty acids to biomass are uncertain. Moreover, these methods can only measure total biomass in a whole sediment sample, and limit the measurement of biomass fraction in individual SPMs. This seminar presents a review of the widely used biomass measurement methods and an introduction to a new approach using PIV and fluorescence application that can systematically measure and detect sediment-attached biomass in single SPMs.

Short Biography
Ms Thu Ha Nguyen is a 1st year PhD student working under the supervision of Dr Federico Maggi at the school of Civil Engineering on the flocculation of sediment particulate matter under influence of biomass variation. Ha obtained her bachelor’s degree (2011) and master degree (2014) in Civil Engineering from Ho Chi Minh City University of Technology, Vietnam. She has been the lecturer at that university since 2011. Her previous research was about modelling of river flow, sediment transport, water supply and drainage system.


Schlieren measurement of temperature in thermal boundary layers

Dr Jingping Wu - Friday 4th November 2016

Abstract
Natural convection has been studied extensively. However, limited experimental data are available for quantifying the transient development of thermal boundary layers. The challenge lies in the quantitative temperature measurement in usually very thin thermal boundary layers. It is well recognized that Schlieren technique based on light deflection through a transparent medium under the influence of temperature/density gradients may provide an alternative means for quantitative temperature and heat transfer measurements. This technique is extremely sensitive and totally non-intrusive. In this study, a quantitative Schlieren technique is applied to investigate convective flow in air and water. The Schlieren system has a Z-type optical setup, in which a noncoherent light beam from a point light source is collimated by a concave mirror to produce a parallel light beam. A test section and a calibration lens are placed in the path of the parallel light beam. A second concave mirror is placed after the test section to refocus the light beam onto a graded-filter, and a DSLR camera is used to capture the image of the test section after passing through the filter. The recorded Schlieren images are then processed to determine the temperature and local heat transfer coefficient. The results from the present experiment are compared with the theoretical data.

Short Biography
Dr. Jingping Wu is an Associate Lecturer in the School of Civil Engineering. She currently works with A/Prof Chengwang Lei on teaching and research in thermal fluid mechanics. She obtained her PhD (2013) and Bachelor degrees (2006) in Energy and Powder Engineering from Wuhan University of Technology in China, and was a visiting PhD student in the School of Mechanical Engineering at the University of Leeds (UK) from 2009 to 2011. Before joining the University of Sydney, she worked as a Postdoctoral Researcher at The University of New South Wales. Her research interests include tribology in bio-engineering systems at macro- and micro-scales; 3D Image acquisition, processing and characterization of engineering and bio-engineering materials; wear debris analysis for fault diagnosis and machine condition monitoring. Her current research focusses on the development of optical techniques for quantitative temperature and flow measurements.


Hydrology of ephemeral catchments:observations and modelling

Dr Edoardo Daly - Tuesday 8th November 2016

Abstract
Land use and land-use change are key drivers of the hydrologic cycle by affecting the vegetation water use of catchment. We report on an on-going project aimed to determine the effects of climate variability and land-use change on water resources in ephemeral productive catchments. Meteorological data, streamflow, and groundwater levels were collected continuously for about 5 years in seven ephemeral catchments in southeastern Australia. The catchments, dominated by either winter-active farm pasture or Eucalyptus globulus (blue gum) plantations with different ages, were located in three different geologic settings. The initial years of the study period experienced annual rainfall higher than the long-term average of this area, while the last couple of years were much dryer than the long-term average. Results from the observation show the effects that topography, geology, climate variability and land use might have on the catchment water balance.
Groundwater levels declined through the study period in all the plantation catchments, while levels in the farm sites remained stable and in some case slightly increased. The estimated evapotranspiration was around 86-115% of the precipitation for all catchments; evapotranspiration rates greater than rainfall in some of the plantations were attributed to access to groundwater or capillary fringe by the trees in some areas of the catchments.
We successfully calibrated and validated the CATchment HYdrology (CATHY) model in two of the catchments. CATHY was used to explore how different root water uptake schemes affect the estimation of the water balance of the catchments.

Short Biography
Dr Daly obtained his PhD in hydraulics from the Politecnico di Torino, Italy; during his PhD, he was a visiting researcher at the Princeton Environmental Institute, Princeton University, USA. After a post-doctoral period in the Pratt School of Engineering and Nicholas School of Environment and Earth Sciences, Duke University, USA, he joined the Department of Civil Engineering at Monash University, where he is currently working as senior lecturer. He was chief investigator in the National Centre of Groundwater Research and Training. Dr Daly’s research efforts in recent years have been focusing on the eco-hydrology of rural and urban catchments using a suite of experimental methods and modelling tools.


Thermocapillary flow in a liquid bridge

A/Prof Liping Yao - Friday 18th November 2016

Abstract
Floating-zone method, which is a unique contactless method avoiding contamination by crucible, is a very important technique for growing high quality semiconductor crystal. Under microgravity, thermocapillary flow driven by unbalanced surface tension on free surface is the dominant mechanism of convection in the floating zone. Instability of the thermocapillary flow may result in macro- and micro-segregation in the grown crystal and in turn the deterioration of crystal quality. Therefore, controlling the thermocapillary flow is very important for growing high quality crystal. Due to the excellent electrical conductivity of semiconductor melt, it is possible to apply an external magnetic field to control the thermocapillary convection. The effect of an external non-uniform rotating magnetic field on the thermocapillary flow in a liquid bridge under microgravity will be discussed in this talk.

Short Biography
Dr Liping Yao is a visiting scholar in the School of Civil Engineering. She is currently working with A/Prof Chengwang Lei on Computational Fluid Dynamics (CFD). She is an Associate Professor in Southwest University, China. She obtained her Bachelor (2006) and PhD (2011) degrees in Engineering Mechanics from Chongqing University, China. Her current research interests include CFD, thermocapillary flows in semiconductor crystal growth, buoyancy driven flows and heat and mass transfer. Her recent research topic focuses on convection control of the thermocapillary flow in a liquid bridge under microgravity.


Performance of a solar chimney with a dual-cavity system

Mr Harrison Jones & Ms Pearl Elgindy - Friday 18th November 2016

Abstract
Providing thermal comfort in the built environment with only the use of energy efficient ventilation systems, specifically natural ventilation using the solar chimney, is the principle idea addressed. Investigated was (i) the flow performance of a dual cavity solar chimney compared to a single cavity, and (ii) the effect of a vertical temperature difference on the airflow. The dual cavity was constructed by partitioning a large single cavity into two smaller cavities using an aluminium foil sheet. The vertical temperature difference was formed by the application of tint to the glass pane of the chimney. Experimental work results in the inlet airflow speed and the speed within the cavities, in addition to CFD simulations conducted will be discussed.

Short Biography
Harrison Jones and Pearl Elgindy are fourth year thesis students currently studying at The University of Sydney.


Natural convection induced by radiation

Mr Abolghasem Naghib - Friday 2nd December 2016

Abstract
In the daytime, incoming solar radiation is absorbed by the water according to Beer’s law. In the near-shore region where the water depth is less than the penetration depth of solar radiation, the residual radiation reaches the bottom and is absorbed there resulting in an adverse temperature gradient which may become unstable. In addition, the distributed solar radiation on water surface and heat exchanges between the water body and ambient are spatially uniform over shallow and deep regions. However, the water depth is shorter in shallow regions compared to deeper regions making the shallow regions warmer than deep regions. This creates a horizontal temperature gradient, leading to a horizontal convective motion. This complex situation contributes to the net transport and mixing between the shore and the deeper regions caused by solar radiation. This is investigated experimentally utilising the flat and sloped bottom tanks and a light source to simulate solar radiation. Concurrent shadowgraph and Particle Image Velocimetry (PIV) are utilised for simultaneous visualisation of the temperature field and flow measurements. As a result, different stages of flow development are identified and characterised quantitatively.

Short Biography
Ghasem Naghib recently finished his PhD at the school of Civil engineering under the supervision of Prof. John Patterson and A/prof. Chengwang Lei. He obtained his Bachelor's degree in Civil Engineering (2006) and his Master's degree in Civil and Environmental Engineering (2010) at Azad University of Mashhad and the University of Tehran in Iran, respectively. He is currently working as a research assistant investigating natural convection near shore of lakes and reservoirs. His research interest area includes hydrodynamic, hydraulic and water quality modelling.