date: 2011 February 23 (Wed) 15:00-16:00
room: Kobe University, Science and Technology Research Building #4-809
speaker: Ichiro Kumagai (Hokkaido University)
organizer: Ayako Suzuki
title: Bubbles save our planet: hydrofoil air pump for drag reduction of ship
abstract: We have invented a new power-saving device for ship drag reduction by microbubbles in order to reduce the energy for bubble injection. The new device, which consists of angled hydrofoils with air introducers, has been installed on a coaster and ~10% net power saving is achieved. This device utilizes a low-pressure region produced above the hydrofoil as the ship moves forward, which drives the atmospheric air into the water. Here we present its principal and fundamental processes such as the entrainment of the air into the water based on laboratory experiments.
title: Flow behavior of thermo-chemical plumes in the Earth's mantle
abstract: We have conducted laboratory experiments on a laminar thermo-chemical plume generated from a thermal boundary layer which is stratified in composition in order to understand mantle plume dynamics. Temperature (TLCs), composition (LIF), and velocity fields (PIV) are simultaneously visualized for quantitative analysis of the flow behavior of thermo-chemical plumes. Because all plumes cool by thermal diffusion as they rise, a chemically composite thermal plume will eventually attain a level of neutral buoyancy, at which it will begin to collapse. Separation within the plume will occur, whereby the chemically denser material will start to sink back while the heated surrounding material keeps rising. We will discuss the behavior of thermo-chemical plumes in the mantle based on its fluid dynamic scaling.