Special Hydrodynamic Features Of Jet Currents In River Mouths
Free (open access)
R. Khanbilvardi, B. Shteinman & O. Ozkurt
The results of measurements as well as theoretical analysis, have led to the revealing of a number of special features of mouth currents: turbulence structure characterized by the presence of a hierarchy of energy supply zones in the velocity spectra; the scales of such zones vary in accordance with degeneration of the river turbulence structure with the advance of the jet current into the receiving water body. The longitudinal dimensions of turbulent eddies get smaller with the distance from the mouth gauge, while their orientation is changing from the predominantly vertical-longitudinal rotation with a horizontal axis to the predominantly horizontal-transversal rotation with a vertical axis. In the zone of mixing river and sea waters, the energy spectra become more narrowband, their ordinates lowering as the river jet moves forward from the mouth, while the maximum spectral density shifts to the area of lower frequencies. Farther from the mouth, in the spectra of the river jet current there appear frequency intervals that can be described not by the known Kolmogorov’s "-5/3" law but by the "-7/3" law. This feature is due to the increasing friction on the side boundaries of the jet. As the river jet moves beyond the mouth bar, another frequency interval appears in the energy spectra; it can be described by the "-3" law. This is attributed to the consumption of energy by the river jet flow for overcoming the ascending forces when the process of vertical mixing of river and sea water masses is going on beyond the bar. Keywords: river mouth, turbulence structure, energy spectra, conceptual physical model.
river mouth, turbulence structure, energy spectra, conceptual physical model.