Seminar "Envelope boundary condition for a flow above the surface of canopy" by Prof. Shintaro Takeuchi

[Speaker]

Dr. Shintaro Takeuchi
Professor
Dept. of Mechanical Engineering
Osaka University

[Abstract]

Boundary condition at the envelope of a layer of flexible fibers (i.e., canopy) subjected to fluid flow is proposed for two-dimensional problem to understand the mechanisms of swaying motion of canopy. By assuming small deflections, the fibers are treated as rigid bars hinged at a flat wall and the effects of the hydrodynamic force on the fibers are expressed with the moment of fluid forces through averaging the Navier-Stokes equation. Envelope displacement is finally represented in a form of mass-spring-damper system driven by the hydrodynamic force. As the nonuniformity of the canopy deformation is enhanced, the effects of diffusion of fiber velocities and fluid inertia along the fibers (i.e. approximately in the wall-normal direction) have more important roles on the time-development of envelope motion. Numerical simulation of fluid flow above the canopy is conducted with the envelope displacement model as the boundary condition at the canopy surface. Through comparison with the results of fluid-structure interaction (FSI) simulation, which solves the interaction between individual fibers and fluid directly by an immersed boundary method, the validity of the present model is assessed. With the envelope model, grid resolution is found to cause little influence on the results, which enables simulation under a coarse resolution such that one fluid mesh size is larger than inter-fiber distance.

[Short biography]

2001: Doctor in Engineering at Dept. Mech. Eng., Osaka University, Japan
2001-2003: Post-doc Fellow at Monash University, Australia
2003-2007: Assistant Professor at Dept. Mech. Eng., Osaka University, Japan
2007-2010: Senior Lecturer at Dept. Mech. Eng., University of Tokyo, Japan
2010-2023: Assoc. Prof. at Dept. Mech. Eng., Osaka University, Japan
2023-Present: Professor at Dept. Mech. Eng., Osaka University, Japan