College of Science & Engineering
These researchers are performing computational studies on the atomization of a class of non-Newtonian fluids, specifically shear-thinning fluids. They study a novel counterflow nozzle geometry, which generates high levels of mixing with low levels of atomizing airflow. In Newtonian flow, countercurrent shear has been experimentally observed to create self-sustained oscillations and strong vortical structures, leading to high mixing rates. The sharp onset of these self-sustained oscillations is strongly connected to the existence of absolutely unstable velocity/property profiles in the flow. The researchers use linear stability theory to study atomization of a non-Newtonian liquid exposed to a counterflowing gas stream inside a duct. The study will identify the dominant wavelengths generated by the relevant parameters, namely the velocity profiles/counterflow rate, liquid power law exponent, Ohnesorge number, density and viscosity ratio, and diameter ratio. The parameter space which yields absolute instability will be replicated experimentally to test for the existence of global modes manifested through self-sustained oscillations, and mono-disperse droplet distribution. The computations use Chebyshev spectral collocation methods implemented in scientific Python, and the eigenvalue solvers built into LAPACK.