2013 Fiscal Year Final Research Report

Dynamical Equations of Aspherical Bubbles Based on Lagrangian Formalism

Research Project

Project/Area Number	23760142
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Multi-year Fund
Research Field	Fluid engineering
Research Institution	Oita University
Principal Investigator	KURIHARA eru 大分大学, 工学部, 准教授 (90344481)
Project Period (FY)	2011 – 2013
Keywords	気泡 / 混相流 / ラグランジュ力学
Research Abstract	The dynamical equations for interacting non-spherical bubbles are derived theoretically in the framework of Lagrangian formalism with multipole expansion of the bubble boundaries. The bubble boundaries are expanded with spherical harmonics so that deformation and translation of the bubbles can be treated. In order to compose the Lagrangian of the system, corresponding amplitudes of the spherical harmonics are chosen as the generalized coordinate. The derived equations show the observed behaviour such as bubble deformation and onset of jetting. The study mainly takes account of the order of the spherical harmonics up to 3rd mode (octupole mode) because octupole mode is the lowest mode oscillation contributing asymmetrical deformation of the bubble and this has the most significant effect on the behaviour of the bubbles.