DEVELOPMENT OF NEW NONLINEAR CONTROLLERS FOR TRAJECTORY TRACKING AND PATH-FOLLOWING OF UNDERACTUATED OCEAN VEHICLES. Trajectory tracking control and path-following of underactuated ocean vehicles are not only of theoretical challenging but also important practice. This project is firstly to develop methodologies to design full-state feedback controllers to force the underactuated ocean vehicles including surface ships and underwater vehicles with off-diagonal terms in their system matrices to tr ....DEVELOPMENT OF NEW NONLINEAR CONTROLLERS FOR TRAJECTORY TRACKING AND PATH-FOLLOWING OF UNDERACTUATED OCEAN VEHICLES. Trajectory tracking control and path-following of underactuated ocean vehicles are not only of theoretical challenging but also important practice. This project is firstly to develop methodologies to design full-state feedback controllers to force the underactuated ocean vehicles including surface ships and underwater vehicles with off-diagonal terms in their system matrices to track reference trajectories generated by virtual vehicles, and to follow a predefined path with a desired forward speed. Secondly, we develop methods to design observers to estimate the unmeasured states (velocities) of the vehicles and incorporate with the full-state feedback controllers to have output-feedback observer-based controllers. Lastly, the proposed control design methods are extended to a certain class of underactuated mechanical systems.Read moreRead less
Coordination control of underactuated ocean vehicles for ocean forecasting. Australia is surrounded by oceans. Ocean forecasting is essential for effective and efficient operations on and within the ocean for a number of applications such as coastal zone management, military operations and scientific research. The successful completion of this project promises to put Australia in a leading position in this area. Due to the multi-disciplinary nature of this project, the project development will a ....Coordination control of underactuated ocean vehicles for ocean forecasting. Australia is surrounded by oceans. Ocean forecasting is essential for effective and efficient operations on and within the ocean for a number of applications such as coastal zone management, military operations and scientific research. The successful completion of this project promises to put Australia in a leading position in this area. Due to the multi-disciplinary nature of this project, the project development will also stimulate the development in many other areas such as new ocean vehicles, sensors and actuators, electronics and control.Read moreRead less
Forecasting wave breaking in directional seas. Wave breaking in Australia's coastal and open ocean regions has significant consequences for weather forecasting, marine safety, defence and renewable energy, yet no conceptual or computing framework exists for this fundamental process. This innovative project extends our recent advances in predicting wave breaking onset and strength of unidirectional wave groups to forecast breaking in realistic directional wind seas. The results of this project wi ....Forecasting wave breaking in directional seas. Wave breaking in Australia's coastal and open ocean regions has significant consequences for weather forecasting, marine safety, defence and renewable energy, yet no conceptual or computing framework exists for this fundamental process. This innovative project extends our recent advances in predicting wave breaking onset and strength of unidirectional wave groups to forecast breaking in realistic directional wind seas. The results of this project will provide the scientific basis needed to include reliable breaking wave information in forecast models, and will improve their accuracy. It will also increase the international competitiveness of Australian commerce reliant on accurate marine environmental forecasts.
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Optimal nose shaping for delayed boundary-layer separation and transition in axisymmetric flow. The aim of this project is to design a smooth nose for a body of revolution placed in axisymmetric flow of a viscous fluid at high Reynolds number, such that the boundary layer on the body remains unseparated. This can always be done with a sufficiently long nose, but our objective here is to minimise the necessary nose length. Outer potential flows will be provided via ring sources. The potential flo ....Optimal nose shaping for delayed boundary-layer separation and transition in axisymmetric flow. The aim of this project is to design a smooth nose for a body of revolution placed in axisymmetric flow of a viscous fluid at high Reynolds number, such that the boundary layer on the body remains unseparated. This can always be done with a sufficiently long nose, but our objective here is to minimise the necessary nose length. Outer potential flows will be provided via ring sources. The potential flows will be used to determine inner boundary layer solutions. Transition-to-turbulence will be considered by undertaking 2D and 3D stability computations.Read moreRead less
Geometry of wall-turbulence and its potential to advance scalable models. This project aims to unravel the connections between the statistical geometry of wall-turbulence and the dynamical interactions of its instantaneous motions. Predicting the complex behaviour of turbulent fluid flow over surfaces in relative motion is central to atmospheric modelling for climate and agriculture, and reducing the environmental effect of fossil fuel usage. Wall-turbulence statistics organise according to a pr ....Geometry of wall-turbulence and its potential to advance scalable models. This project aims to unravel the connections between the statistical geometry of wall-turbulence and the dynamical interactions of its instantaneous motions. Predicting the complex behaviour of turbulent fluid flow over surfaces in relative motion is central to atmospheric modelling for climate and agriculture, and reducing the environmental effect of fossil fuel usage. Wall-turbulence statistics organise according to a predictable geometric structure, and the notorious complexity of turbulent wall-flow dynamics could be clarified through its inherent geometry. This project expects to construct a basis for predicting engineering and atmospheric wall-flows, which would enhance atmospheric flow prediction, reduce energy consumption and further environmental sustainability.Read moreRead less
Self-similar scale interactions in turbulent boundary layers. Predicting and controlling turbulent fluid flow next to a solid surface (the turbulent boundary layer) is of critical importance to ensuring a sustainable energy and environmental future. While recent research has yielded a clearer physical understanding of these flows, converting this understanding into tools useful to engineering practice remains a central obstacle. The proposed research directly addresses this fundamental challenge ....Self-similar scale interactions in turbulent boundary layers. Predicting and controlling turbulent fluid flow next to a solid surface (the turbulent boundary layer) is of critical importance to ensuring a sustainable energy and environmental future. While recent research has yielded a clearer physical understanding of these flows, converting this understanding into tools useful to engineering practice remains a central obstacle. The proposed research directly addresses this fundamental challenge by precisely connecting the eddy interactions of the turbulence to the mathematical equations that rigorously describe these flows. As such it holds breakthrough potential toward the development of turbulent boundary layer prediction and control schemes that do not rely on ad hoc models or assumptions.Read moreRead less
Airfoil Noise Control in Complex Turbulence. This project aims to understand how to control noise created by the interaction of airfoils with complex, real-world turbulence. This project is significant because it will develop novel serrated and porous leading edges tailored for complex turbulence for the first time. Using innovative experimental and theoretical techniques, the project will dramatically advance the science of aeroacoustics. The expected outcomes of the project will be substantial ....Airfoil Noise Control in Complex Turbulence. This project aims to understand how to control noise created by the interaction of airfoils with complex, real-world turbulence. This project is significant because it will develop novel serrated and porous leading edges tailored for complex turbulence for the first time. Using innovative experimental and theoretical techniques, the project will dramatically advance the science of aeroacoustics. The expected outcomes of the project will be substantial reductions in noise from aircraft, wind turbines, submarines and drones. This will provide significant benefits such as a reduction in environmental noise pollution, better public health and submarines with increased stealth.Read moreRead less
Understanding and predicting airfoil noise in real-world turbulence. This project aims to understand and predict the noise produced by turbulence interacting with an airfoil to advance the design of aeroengines, wind turbines, marine vessels, cooling fans and drones. A novel anechoic wind tunnel experiment is proposed to link complex turbulent in-flow with the behaviour of the flow as it interacts with the airfoil and the noise-producing physics. The intended outcomes of this project are new sem ....Understanding and predicting airfoil noise in real-world turbulence. This project aims to understand and predict the noise produced by turbulence interacting with an airfoil to advance the design of aeroengines, wind turbines, marine vessels, cooling fans and drones. A novel anechoic wind tunnel experiment is proposed to link complex turbulent in-flow with the behaviour of the flow as it interacts with the airfoil and the noise-producing physics. The intended outcomes of this project are new semi-analytical noise prediction models and scientific knowledge that can be harnessed for practical noise control. Anticipated benefits include quiet aerospace, naval and renewable energy technologies, reduced environmental noise pollution and better quality of life.Read moreRead less
Elucidating the inertial force mechanisms of turbulence. The turbulent flow of fluids (for example, air, water) near a solid surface is of enormous technological importance. The proposed research will advance engineering prediction and control capabilities by revealing how the unsteady eddying motions produce the apparent inertial force that distinguishes turbulent flows from their laminar counterparts.
Advancing a first-principles basis for the prediction and manipulation of turbulent wall-flow transport. This project aims to advance the design of energy efficient and environmentally friendly processes and devices by developing analysis tools that tell us how to predict and control the heat and momentum transport caused by turbulent flow near a solid surface. The expected outcomes are ways to accomplish these aims via the direct use of the basic physical laws.