University of Massachusetts Amherst

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Computational simulations of multi-phase flows and application in ocean wave energy conversion and atmospheric icing


Monday, November 9, 2015 - 4:00pm


Mehdi Raessi, Ph.D., Assistant Professor, UMass Dartmouth


Kellogg Room, Elab II


In this talk, I will present our computational results in two areas: (a) ocean wave energy conversion, and (b) atmospheric icing. I will briefly discuss our incompressible, multi-phase flow solver, which is MPI-parallel and GPU-accelerated, and highlight its recently-added capability to capture the interaction between moving rigid solid bodies and a flow of two immiscible fluids.  A three-dimensional, volume-of-fluid (VOF) method for tracking three material volumes and resolving contact lines is also presented.  Then, I will discuss an application of the above flow solver in the area of ocean wave energy conversion and present simulation results of a bottom-hinged, flap-type wave energy converter (WEC) and a point-absorber WEC. In the second half of the talk, I will present our ongoing work on atmospheric icing, which focuses specifically on the impact of water droplets onto freezing super-hydrophobic surfaces. Forming dimensionless groups and varying important parameters in our computational simulations, we have identified conditions under which a water droplet is able to bounce off the surface before freezing, i.e., the surface becomes “ice-phobic”. We combined this computational study with a theoretical dimensional analysis, which compares the time-scales for droplet freezing and the droplet-surface contact. The result is a theoretical model that predicts very well the conditions under which a super-hydrophobic surface becomes ice-phobic.

Mehdi Raessi is an Assistant Professor in the Mechanical Engineering Department at the University of Massachusetts Dartmouth. He joined UMass Dartmouth in 2010 following a two-year postdoctoral study at the NASA/Stanford University’s Center for Turbulence Research. He obtained his Ph.D. in Mechanical Engineering from the University of Toronto in 2008, where he was a research assistant in the Centre for Advanced Coating Technologies. Dr. Raessi’s research focus is primarily on interfacial flows and free-surface flows with phase change. His research group develops and utilizes numerical methods to study interfacial flows in various industrial and research applications including energy systems, materials processing and manufacturing, and underwater oil leaks.