There are no simple answers to these problems and the economic questions they engender. It is evident, however, that these problem areas will become increasingly important as a field of engineering practice and of engineering science research; and that this will be the case well into the 21st Century. Energy conservation, increased energy efficiency and cleaner use of fossil fuel energy resources will play a key role in the next 40 years.
The postgraduate research program at the University of Sydney in the Department of Mechanical and Mechatronic Engineering is firmly committed in the long term to developing the engineering tools needed by the engineering profession in these areas. Our approach focuses on the further development of Computational Fluid Dynamics (CFD) as the primary tool for application of fundamental science to these complex engineering problems that typically involve turbulent flows, chemical reactions, heat transfer and particle dynamics.
Current CFD methods are, however, far from quantitative when it comes to the prediction of pollutant emissions. This is largely due to the problems of combustion / turbulence interactions: turbulence causes strong fluctuations in species concentrations and temperature so that conventional approaches using averaged conservation equations become intractable; and in turn the heat release associated with the reactions affects the turbulent mixing and transport processes. This is a long-standing classical problem in this field.
The research group working with Professor Robert Bilger has made significant contributions in theoretical, experimental and computational studies of the turbulence/combustion interaction problem over the last 25 years. Conserved scalar theory and the Conditional Moment Closure (CMC) approach are advances that have achieved wide-spread international recognition. They are currently being implemented into professional CFD codes. A complementary approach using Monte Carlo simulation of the PDF transport equation is being pursued by Dr Assaad Masri in collaboration with Professor Stephen Pope at Cornell University.
A notable feature of the research at Sydney has been the strong experimental basis for the modelling development work. Laser-based measurements in flames have been made in our laboratory for more than 20 years. Our current Multi-species Imaging Facility is among the leading measurement capabilities of this type in the world. Collaboration with other leading laser diagnostic facilities around the world is also strong, particularly with Sandia National Laboratories at Livermore, California and with Yale University. Emphasis has been placed on both the elucidation of flame structure and on obtaining quantitative measurements in well-defined flows for model validation. Collaboration with the Workcover Authority of NSW at their Londonderry, NSW fire gallery has generated important data in large-scale fires.
Numerical experimentation can also be effectively used in the development of models of combustion/turbulence interactions. In 1995 we have begun work on Direct Numerical Simulation (DNS) of turbulent reacting flows using local advanced workstations. Collaboration with the NASA Ames/ Stanford University Center for Turbulence Research (CTR) gives us input to and output access to DNS calculations on the C90 and other supercomputers of the US National Aerospace Simulator.
For CFD calculations and model development a range of workstations are in use. Integration of these into a distributed parallel processing facility using the Oak Ridge PVM software is being implemented.