Acoustic microstreaming near a plane wall due to a pulsating free/coated bubble: Nyborg result revisited and vortices

TL;DR

This paper analytically investigates acoustic microstreaming caused by oscillating microbubbles near a wall, revisiting Nyborg's classical theory to analyze flow fields, vortices, and shear stresses.

Contribution

It revisits and extends Nyborg's classical theory to analyze microstreaming near walls, providing detailed flow and vortex insights.

Findings

Vertex length decreases near the wall

Maximum shear stress increases near the wall

Flow field and vortices are characterized analytically

Abstract

Acoustic microstreaming due to an oscillating microbubble is analytically investigated to obtain the circular streaming motion adjacent to a nearby wall. Classical theory due to Nyborg is carefully derived in the radial coordinates. The theory is used to obtain the flow field and the vortical motion caused by the microbubble motion. The length of the vertices are decreasing when the microbubble is excited at distances close to the rigid wall, while the maximum shear stress is increasing.