Date of Award
Physics and Astronomy
Cavitation is the result when there are rapid changes in pressure in a liquid. These vapor-filled cavities can occur when ultrasound propagates through water at sufficient power. The volumes of these cavities can pulsate and can even couple with the radiation pressure from the ultrasound. The result is a translational force on the bubbles. This translational force on the bubble is called the primary Bjerknes force. The secondary Bjerknes force is the result of two pulsating cavities, but this force is ignored since the buoyant force and the primary Bjerknes force are the dominant forces. Immediately before a bubble begins to rise, the net force on the bubble is equal to zero. Therefore, the primary Bjerknes force and the buoyant force are equal. The primary Bjerknes force can be indirectly measured by measuring the diameter (and thus the volume) of a bubble immediately before it rises. Diameters of bubbles were measured using a video camcorder and an open-source program called ImageJ. Three sets of data were taken. Each set of data includes four critical bubbles. The primary Bjerknes force ranges from 0.15 μN to 0.41 μN. Recent research and future work are discussed.
Smith, Mason, "Measurements of the Primary Bjerknes Force in a Cavitating Ultrasonic Field" (2019). Honors Theses. 1144.