[PhD Thesis Public Presentation_C700, Lab3_Zoom is also available] ‐ Ianto Cannon– “Simulations of Multiphase Turbulent Flows”

Presenter: Ianto Cannon

Supervisor: Prof. Marco Edoardo Rosti

Unit: The Complex Fluids and Flows Unit

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Title: Simulations of Multiphase Turbulent Flows

Abstract:

The flow of an incompressible fluid can be described exactly and succinctly using the Navier-Stokes equation. However, the nonlinearity of this equation leads to flow structures with detail at many length scales, known as turbulence. The only exact theory in turbulence was made in 1941 by Kolmogorov. In this thesis, we probe Kolmogorov's predictions in the case of multiphase systems by making direct numerical simulations of droplets, particles, and solid phases in turbulent flows. Firstly, we show how the coalescence of droplets can reduce drag in a turbulent channel flow. Following on from this, in the remainder of the thesis we look more closely at the turbulent energy cascade using simulations of statistically homogeneous and isotropic flows. We show that isotropic and anisotropic particles couple to the cascade at different length scales. Next, we show that the plasticity of a fluid enhances its turbulent behaviour. Finally, we investigate the breakup and coalescence of droplets in the presence of the turbulent cascade. The results presented in this thesis find cases in which Kolmogorov's predictions do not hold. In each case, we aim to explain why. These results can have wide-reaching implications for industry and the environment, including heart disease, micro-plastic dispersal, mudslides, and cloud formation.