Bubble Image Velocimetry with an Acoustic Camera
Abstract
BIV is a subset of particle image velocimetry (PIV), a common laboratory experimental technique used to measure flow velocity. In traditional particle image velocimetry, the flow of interest is seeded with tracer particles that reflect light and are assumed to faithfully follow the motion of the fluid, which is a valid assumption with sufficiently small particles (Adrian and Westerweel 2011). In BIV, bubbles are used in place of tracer particles (Ryu et al. 2005). In either case, the motion of the tracer particles/bubbles is observedgenerally with a charge-coupled device or complementary metal-oxide semiconductor digital camera for modern systemsand used to quantify the flow velocity. The flow velocity is measured by sub-dividing the camera images into windows (e.g., 16 16 pixels); then, cross-correlation is used to determine the aggregate displacement of all the particles in each window between successive images (Raffel et al. 2007). However, traditional PIV and BIV measurement techniques with an optical camera are difficult to deploy in the field because they are equipment intensive, require stationary, well-calibrated images, and can only be performed in a reasonably transparent fluid (such that the optical camera can see the tracer particles/bubbles). Obviously these requirements quickly become restrictive in field deployments, particularly in highly turbid environments near dredging operations.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 2019
- Accession Number
- AD1074587
Entities
People
- Brian C McFall
- David L. Young
- Duncan B. Bryant
Organizations
- Engineer Research and Development Center