My expertise is in the scientific study of multi-phase fluid flows, and the application of advanced optical and x-ray diagnostics to these problems.

Multi-phase flows are any combination of two or more phases of matter (i.e. solid, liquid, and gas) moving together. There’s a lot we don’t yet know about how these kinds of fluid flows behave, because they are very difficult to experiment on. You can’t make a scale model of the fluid flow like you can with a car in a wind tunnel, and when you shine light through most multiphase flows, it scatters a lot, and this makes it very hard to make accurate observations. We’re addressing these challenges by developing new ways to use synchrotron x-ray light, advanced laser diagnostics, and computer models.

Understanding how multi-phase flows behave is essential to the development of technologies that we rely on every day. For example, multi-phase flows determine:

• How well your athsma inhaler works – Aerosol and powder inhalers involve small droplets or particles moving in air. The turbulence of the air and the complexities of the evaporation process for propellant-driven sprays, among other factors, makes the particles’ properties very difficult to predict.
• How efficiently your car engine runs – The fuel injectors in an engine create a fine mist which is then burned. The spray quality directly affects power output and pollutant formation. The fuel can even boil or cavitate inside the injector, wearing out the components.
• The environmental impact of your air conditioner – The refrigerant fluid inside an AC, fridge or freezer boils and is re-condensed over and over. The dynamics of this process affect how much energy it uses to move a given amount of heat, and how long the parts will last before they wear out. The refrigerant fluids used in these devices can be harmful to the atmosphere if released, so finding more environmentally-friendly alternatives and understanding how they behave is important.

A better understanding of multi-phase flows will help us to make these technologies more energy-efficient and environmentally-friendly, as well as expand our understanding of how the natural world works. These problems are becoming more important as the number of people worldwide using technologies like those listed above is rapidly increasing. At the same time, our society is becoming increasingly aware of the environmental cost of energy consumption and air pollution.

Computer simulation of fuel cavitating inside a model of a fuel injector nozzle. Credit: D. Duke, C. Powell & D. Schmidt. The simulation was performed on the “Blues” cluster at Argonne National Laboratory.

Mie-scatter image of a spray produced by a pressurised metered-dose medical inhale. Credit: N. Mason-Smith, D. Edgington-Mitchell, D. Honnery, D. Duke & J. Soria (2015). Proc. TSFP-9 Int Symposium on Turbulence and Shear Flow Phenomena.

Computer simulation (top row) and high speed images from laboratory test (bottom row) of a flash-boiling gasoline fuel injection spray. Credit: E. Baldwin, R. Grover, S. Parrish, D. Duke, K. Matusik, C. Powell, A. Kastengren and D. Schmidt (2016). Int J Multiphas Flow 87 pp. 90-101.

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