抄録
In the present study, the authors investigate an oscillatory phenomenon of a two-dimensional confined jet with a downstream target, by experiments and computations. By experiments in air and water, we perform the measurements by a hot-wire anemometer, an ultrasonic velocity profiler and a particle-image velocimetry at the Reynolds number Re < 5000. In computations, we discretise the two-dimensional Navier-Stokes equations by a finite difference method formulated in terms of vorticity and stream function. As a result, we reveal the influences upon the jet's oscillation frequencyf of (1) Re, (2) the target-distance, (3) the target-size and so on, where f is non-dimensionalised as the Strouhal number St(b). Regarding the Re effect, we can neglect it. This guarantees wide-range workability as a flowmeter or a mixer. All the results can be summarised in an empirical formula describing the relation between St(b) and geometrical parameters.
