Fundamental Properties of Flows in a Precessing Sphere

2015 Fiscal Year Final Research Report

• Project/Area Number: 24540416
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Mathematical physics/Fundamental condensed matter physics
• Research Institution: Doshisha University
• Principal Investigator: KIDA Shigeo 同志社大学, 研究開発推進機構, 嘱託研究員 (70093234)
• Co-Investigator(Kenkyū-buntansha): GOTO Susumu 大阪大学, 基礎工学研究科, 教授 (40321616) ; SIMIZU Masaki 大阪大学, 基礎工学研究科, 助教 (20550304)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: 歳差回転球 / 安定性 / 臨界帯 / 不規則反転

Outline of Final Research Achievements

An incompressible viscous fluid in a precessing sphere exhibits a variety of states from laminar to turbulent flows, depending upon two non-dimensional parameters (the Reynolds number and the Poincare number)defined in terms of the sphere radius, the spin angular velocity, the precession angular velocity and the kinematic viscosity of fluid. Here, we examined the structure and the existence condition of the steady flow. An asymptotic analysis was performed to obtain the structure of a pair of vortices localized in the vicinity of the great circle perpendicular to the precession axis. We determined the existence boundary of the steady flow over the whole parameter space by means of direct numerical simulation and asymptotic analysis. Moreover, a series of random reversals of the velocity field was observed.

Free Research Field

流体物理学