An investigation of wave-amplitude vacillation using a light-speckle velocity measuring technique

A novel form of streak photography based on a light-speckle technique has been used to investigate wave-amplitude vacillation in a thermally driven rotating cylindrical annulus of fluid. The technique is evaluated and found to be an excellent way to measure a 2-dimensional field of velocity without introducing probes into the fluid. The results are compared with previous work that used 98 probes. The flow without probes is similar to the previous work with the exception that the kinetic energy is significantly higher. The relation between eddy and mean motion, momentum transport, and period of the vacillation cycle appear similar in the two studies.