卷跃波浪破裂的实验流体力学(EFD)和计算流体力学(CFD)研究
A complementary experimental and computational study of plunging breaking waves is presented that are generated ina two dimensional open channel flume using a bottom bump and impulsive accelerated flow. The time evolution of the transientwave and its flow properties are measured using experimental fluid dynamics (EFD): upstream and downstream velocityand flow rates using pitot probes air-water interface elevation measurements and two dimensional particle image velocimetryin the wave breaking region. The computational fluid dynamics (CFD) methods are: Cartesian grid embedded-boundary hybrid HSM/GF/particle level set and VOF methods, and LES. CFD wave profiles at various time stepsidentifies the overall wave breaking process and major events: max wave height, first plunge, oblique splash-up, vertical jet,air entrainment, two repeats of these processes, dissipation and wave swept downstream which is qualitatively validated byEFD results. Both EFD and CFD results showed two subsequent plunging and splash-up events after the first plunge. Afterthe wave breaks, the flow trends in mean velocity and vorticity observed in EFD are very similar to CFD which has moredetailed resolutions of plunging, splashing, vertical jet and bubble entrainment. Current studies also revealed the occurrenceof chaotic multiple splash-up events after the third plunging that produce span-wise vorticity and turbulence. Generation ofa clockwise rotating bump vortex and an anticlockwise rotating span-wise wave breaking vortex that is created from theentrapped air after the breaking which transports turbulence from the trough towards the bulk fluid, were identified as thetwo important events. Mean values of turbulent kinetic energy (TKE) below the broken wave showed that the TKE levelsincrease by almost 90% after the first plunge and another 40% after the second plunge, after which as the wave is sweptdownstream by the accelerating mean flow the TKE dissipates.