Dynamics of a toroidal bubble on a cylinder surface with an application to geophysical exploration. (August 2020)

• Record Type: Journal Article
• Authors: Li, Shuai; Prosperetti, Andrea; van der Meer, Devaraj
• Is Part Of: International journal of multiphase flow. Volume 129(2020)
• Publication Date: 2020-08
• Subjects: Bubble dynamics -- Seismic airgun source -- Boundary integral method -- Geophysical exploration -- Fluid-structure interaction; Multiphase flow -- Periodicals; Écoulement polyphasique -- Périodiques; Multiphase flow; Periodicals; 620.1064
• DOI: 10.1016/j.ijmultiphaseflow.2020.103335
• Languages: English
• ISSNs: 0301-9322

Abstract

Highlights: The interaction between a cylinder and an attached toroidal bubble is modeled using BIM. Three types of bubble collapse patterns are identified, namely upward jet, annular jet and no jet. The effects of governing parameters on the bubble dynamics and pressure waves are studied. The impact of a cylinder on a Sercel type airgun-bubble is investigated. Abstract: During the operation of a seismic airgun source, a certain amount of compressed high-pressure air is released from the airgun chamber into the surrounding water, generating an expanding toroidal bubble attached to the airgun-body. The subsequent oscillations of the bubble generate low-frequency pressure waves, which are used to map the ocean subbottom, e.g., to locate oil and gas reserves. The bubble dynamic behavior and the emitted pressure waves are inevitably influenced by the airgun-body. However, the bubble-airgun-body interaction is far from well understood. This paper investigates the strong interaction between a long cylinder and an attached toroidal bubble via hundreds of boundary integral simulations, aiming to provide new physical insights for airgun-bubble dynamics. Firstly, the overall physical phenomena are discussed and three types of bubble collapse patterns are identified, namely (i) upward jetting due to gravity, (ii) annular jet toward the cylinder body and (iii) weak/no jet. Thereafter, we investigate the effects of the cylinder radius, initial bubble pressure and Froude number on the bubble oscillation period and the pressure wave induced by the bubble. At last, the impact of a cylinder on a Sercel type airgun-bubble is discussed with a particular focus on the spectrum of the pressure waves.