FLOOD FLOW CHARACTERISTICS AND BED LOAD TRANSPORT IN NON-VEGETATED COMPOUND STRAIGHT CHANNELS

2016 ◽  
Vol 78 (9-4) ◽  
Author(s):  
Mazlin Jumain ◽  
Zulkiflee Ibrahim ◽  
Zulhilmi Ismail ◽  
Mohd Fuad Samsudin ◽  
Muhd Zubair Tajol Anuar ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Bed Load ◽  
Mobile Bed ◽  
Load Transport ◽  
Bed Load Transport ◽  
Flow And Sediment Transport ◽  
Depth Increase ◽  
Bed Slope ◽  
Overbank Flows ◽  
Flood Flow

Floods are the most common natural disasters in Malaysia and have damaged structures, infrastructures, crops and even causes fatalities. It may also lead to erosion and sedimentation in rivers and this will result to complex river behaviour.  A hydraulic laboratory experimental study was carried out. Also, flood flow and sediment transport in straight compound channels involving flow resistance, distribution of depth-averaged velocity, stream-wise vorticity patterns, channel bed morphology and bed load transport rate in non-vegetated compound straight mobile bed channels were investigated. The finding showed that the Darcy Weisbach friction factor  f  increased by 40% and 54% for floodplain and main channel, respectively when relative flood flow depth increase from 0.30 to 0.50. The small bed load transport rates of 0.09 g/s and 0.03 g/s for shallow and deep overbank flows, respectively were measured due to effect of very gentle or mild channel bed slope which was fixed at a gradient of 0.1%. 

Physical and Mathematical Modeling of Solid-Liquid Flow at High Bed Shear in Steep Flume

2015 ◽  
Author(s):  
Václav Matoušek ◽  
Štěpán Zrostlík ◽  
Jan Krupička ◽  
Tomáš Picek ◽  
Vojtěch Bareš
Keyword(s):  
Mathematical Modeling ◽  
Flow Rate ◽  
Open Channel ◽  
Bed Load ◽  
Flow Depth ◽  
Load Transport ◽  
Bed Load Transport ◽  
Bed Slope ◽  
Solid Liquid ◽  
Bed Friction

The paper discusses new results of our experimental- and mathematical modeling of sediment-laden open-channel flows in the upper plane bed regime associated with intense transport of sediment. Our recent studies showed that bed-load transport and bed friction are interrelated and classical formulae for bed friction (Nikuradse formula) and bed-load transport (Meyer-Peter and Muller formula) need to be modified to account for the intense transport of sediment. The new results of our laboratory experiments in a tilting flume are presented and analyzed for different sediment fractions. The analysis is focused on the effect of solids density and size on the solid-liquid flow characteristics as the solids flow rate, flow depth, and bed slope for certain flow rate of water in a channel of given geometry. The experimental results are compared with outputs of our mathematical model simulating the observed phenomena. The simple 1-D model combines hydrodynamic- and sediment-transport equations and enables to use different transport- and friction formulae to predict the solids transport, flow depth and bed slope under the condition of (pseudo-) uniform flow of solid-water mixture in the open channel.

The formation of ripples and dunes on an erodible bed

1980 ◽  
Vol 99 (3) ◽  
pp. 597-618 ◽  
Author(s):  
Kelvin J. Richards
Keyword(s):  
Eddy Viscosity ◽  
Roughness Length ◽  
Present Theory ◽  
Bed Load ◽  
Low Froude Number ◽  
Load Transport ◽  
Bed Load Transport ◽  
Bed Slope ◽  
Two Parameters ◽  
Good Agreement

A two-dimensional stability analysis is presented of flow of low Froude number over an erodible bed. Particular regard is given to the modelling of the turbulent flow close to the bed. In contrast to previous theories that use a constant eddy-viscosity approach the present theory predicts the occurrence of two separate modes of instability, with wavelengths related to the roughness of the bed and the depth of the flow. It is postulated that these two modes correspond to the formation of ripples and dunes respectively. The results are strongly dependent on the two parameters z0, the roughness length of the bed, and β, the effect of the local bed slope on the bed-load transport. Using physically plausible estimates for these parameters the results of the analysis are in good agreement with observations for both ripples and dunes.

scholarly journals Experimentally determined distribution of granular-flow characteristics in collisional bed load transport

2018 ◽  
Vol 180 ◽  
pp. 02061
Author(s):  
Václav Matoušek ◽  
Štěpán Zrostlík ◽  
Luigi Fraccarollo ◽  
Anna Prati ◽  
Michele Larcher
Keyword(s):  
Two Phase Flow ◽  
Imaging Techniques ◽  
Local Level ◽  
Flow Characteristics ◽  
Transport Layer ◽  
Bed Load ◽  
Phase Flow ◽  
Two Phase ◽  
Load Transport ◽  
Bed Load Transport

A series of laboratory experiments on turbulent open-channel two-phase flow in a form of intense bed load transport is reported. Measurements in a laboratory tilting flume included camera based imaging techniques to identify the structure of the flow at the local level. Obtained experimental distributions of two-phase flow related parameters - granular velocity, concentration, and temperature - across a collisional transport layer are discussed. The results are analysed together with additional measured quantities (discharges of mixture and grains, flow depth, bed slope etc). Our major goal is to evaluate the distribution of granular stresses across the transport layer with a special attention paid to the interface between the transport layer and the bed. Furthermore, comparisons are discussed between the experimental results and predictions produced by suitable kinetic-theory based models.

NUMERICAL MODEL TO SIMULATE THE EROSION ON THE SLOPE DUE TO OVERTOPPING

2010 ◽  
Vol 13 (3) ◽  
pp. 78-87
Author(s):  
Hoai Cong Huynh
Keyword(s):  
Numerical Model ◽  
Flow Model ◽  
Bed Load ◽  
Experiment Data ◽  
Step Method ◽  
Morphological Model ◽  
Load Transport ◽  
Bed Load Transport ◽  
The Finite Difference Method ◽  
Good Agreement

The numerical model is developed consisting of a 1D flow model and the morphological model to simulate the erosion due to the water overtopping. The step method is applied to solve the water surface on the slope and the finite difference method of the modified Lax Scheme is applied for bed change equation. The Meyer-Peter and Muller formulae is used to determine the bed load transport rate. The model is calibrated and verified based on the data in experiment. It is found that the computed results and experiment data are good agreement.

scholarly journals Experimental Study on Bypassing Tunnel of Bed Load Transport in a Reservoir

1996 ◽  
Vol 40 ◽  
pp. 813-818
Author(s):  
Minoru HARADA ◽  
Kazuo ASHIDA ◽  
Takashi DENO ◽  
Yuji OHMOTO
Keyword(s):  
Experimental Study ◽  
Bed Load ◽  
Load Transport ◽  
Bed Load Transport
Sign in / Sign up

Export Citation Format

Share Document