Abstract: Cavitation phenomena and underwater noise mechanism are closely related to bubble dynamics. Under the assumption of inviscid potential flow, a multiple parameter perturbation analysis is carried out for the nonlinear volume mode oscillation of a 3D gas bubble moving in a slowly varying flow in the paper. The perturbation equations are deduced by expanding the nonlinear boundary conditions to be satisfied on the slowly varying shape. The evolution equation and some analyticalsolutions of the first order osc...