Variation of Velocity Distribution in Rough Meandering Channels

Abstract

Distribution of flow and velocity in a meandering river is important in river hydraulics to be investigated from a practical point of view in relation to the bank protection, navigation, water intakes, and sediment transport-depositional patterns. When flow enters a bend, the centrifugal force arising from the channel curvature leads to a transversal slope in the water surface. The interaction between the centrifugal force and transversal pressure gradient causes secondary flows in cross-sections, and the secondary flows spread further by moving along the bend. Hence, at the bends, these processes lead to longitudinal velocity increase in the inner wall and decrease at the outer wall. In this paper, experimentation is carried out for two different bed roughness on a 4.11 sinuosity meandering channel with 110° crossover. Longitudinal velocity distribution is analysed with the graphical illustrations for the detailed experimental study. Study of flow profile across the crossover is also particularly important as the inner bank of the bend changes to the outer bank and vice versa which has a significant effect on the water surface profile and hence on the velocity distribution along the full meander path. The objective of the analysis is to determine the effect of curvature and roughness on the velocity profiles, throughout the meander path. It is determined that the resistance of flow, on the smoother bed channel, is higher than that of the channel with higher Manning’s n above a certain depth at the apex and transition sections. A reciprocal study of the experimental investigation is attempted with a numerical hydrodynamic tool, namely, CCHE (Centre for Computational Hydroscience and Engineering) developed by NCCHE, University of Mississippi, US. The model is applied to simulate the inbank flow velocity distribution and validate the experimental observation for the meandering channel with rough bed.

Numerical and Experimental Analysis of Shear Stress Influence on Cellular Viability in Serpentine Vascular Channels

“…Resultant interaction between Coriolis force and transversal slope develops a secondary force on the flow cross-section. This secondary force had disseminated to the curvature section, producing a higher axial velocity magnitude [ 52 ]. Maximum axial velocity and presence of curvature of proposed serpentine structure were the effective parameters for developing maximum pressure near the neck and rear region of the serpentine structure at the end of T cycle.…”

Assessment of meander‐bend migration of a major distributary of the Ganges River within Bangladesh

“…When a single‐thread channel of a river flows winding across its floodplain, a series of reversing curves form with varied sizes and shapes and leave a footprint of its course in an oscillatory path with a zigzag pattern known as a meandering river. The flow of water through the bend of a mender river produces centrifugal acceleration, resulting in a high‐velocity flow field toward the outer bank (Pradhan et al, 2018; Rhoads, 2020). A secondary circulation also develops along the cross‐section of the bend near the riverbed toward the inner bank and near the free surface toward the outer bank (Ferguson et al, 2003; Shaheed et al, 2021).…”

Analysis of Multifactor Influence Model on Energy Dissipation Rate of Rough-Strips Energy Dissipator in the Spillway Bend

“…In terms of prototype observation, some scholars make actual measurements on the observation data of natural bends [3][4][5], and taking into account the geographical location restrictions and measurement accuracy, most scholars now use indoor test method. For physical model tests, some scholars studied macroscopic features, such as the structure, turbulence characteristics, hydraulic characteristics of bend flow by conducting different types of model tests and combining with theoretical analysis [6][7][8][9][10][11][12][13][14]; and in terms of numerical simulation, some scholars have established two-dimensional or three-dimensional bend flow mathematical models by using a variety of algorithms, such as the finite volume method, and compared with the model test to verify, supplement the model test shortcomings, and analyze the characteristics of bend flow from a microscopic point of view [5,[8][9][10][11][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Previous studies have mostly focused on hydraulic characteristics of flow in bends, and some scholars have put forward engineering auxiliary measures to improve flow conditions in bends, such as vanes [27,28], guide walls [29], spur dikes [30,31], riprap [32], etc.…”