Ultrasonic Acoustic Characteristics of Air Bubbles in the Surf Zone

摘要

Understanding the movement of sediment in the nearshore region due to wave motionand longshore currents is important in beach erosion studies, and has tactical significance in beach front mine warfare. Using ultrasonic acoustic backscatter, the Coherent Acoustic Sediment Flux Probe (CASP) is capable of tracking the movement of scatterers within the surf zone. Laboratory experiments were run to determine the ultrasonic acoustic backscatter characteristics of surf zone bubbles. Bulk void fraction and optical sizing methods were explored to develop a means of measuring bubble populations produced in the laboratory for calibration of the backscattered energy received by the CASP system in the presence of bubbles.