Experimental Results from Bore Phenomenon in Open Cylindrical Channel under Precession

Hajar Alshoufi

doi:10.4236/ojfd.2022.121004

Abstract

Experimental campaigns were carried out to extract results from the flow in an open cylindrical channel under precession. The bore or the hydraulic jump is the main concentration. The experimental results are varied; this includes velocity results and geometrical ones related to the depths, phases, and lengths. For the geometrical ones a Coupled-Charged Device Camera (CCD) is used to extract pictures, those enable us to get quantitative and qualitative results. For the velocity results, Acoustic Doppler Velocimeter (ADV) is used to extract the velocity signals under the bore surface, after analyzing them it turned out that they have Cnoidal form, thus a new BBM model is derived, which is exactly as the one derived by Peregrine (1966), the only difference is the forcing gravity term, this model is solved analytically after omitting this gravity term as it is considered small, and the solution is compared with the real signals with good match. Finally, a new relationship that connects between the conjugate depths after and before the bore is derived which has time-space dependency due to the Centrifugal effect, it was also used and compared with some experimental results.

Highlights

It is well known that the transition between two levels of water have different aspects, it can be totally broken highly agitated and turbulent which is wellknown phenomenon as bore or hydraulic jump, and sometimes this level is covered by smooth periodic undulations called the dispersive shock waves or undular bores [1]
The experimental results are varied; this includes velocity results and geometrical ones related to the depths, phases, and lengths
Acoustic Doppler Velocimeter (ADV) is used to extract the velocity signals under the bore surface, after analyzing them it turned out that they have Cnoidal form, a new BBM model is derived, which is exactly as the one derived by Peregrine (1966), the only difference is the forcing gravity term, this model is solved analytically after omitting this gravity term as it is considered small, and the solution is compared with the real signals with good match

Summary

Introduction

It is well known that the transition between two levels of water have different aspects, it can be totally broken highly agitated and turbulent which is wellknown phenomenon as bore or hydraulic jump, and sometimes this level is covered by smooth periodic undulations called the dispersive shock waves or undular bores [1]. The experiments of Favre stimulated other researchers to study this topic, for instance, in [4] the authors performed two experimental campaigns on the surges moving from a reservoir through rectangular contraction into an open channel that was given different slopes, the first one used a light metal planing plate with different loads over the surface to maintain the first wave, and a train of undular waves can appear. Other experiments were carried out in [5], the main concentration was the surface configuration of breakers, bores, and hydraulic jumps in flumes with transparant sides, which are considered different modes of quasi-steady breaking waves, their observations indicates that the surface roller does not play a dominant role in the dynamics of the wave

Methods

Results

Conclusion