Laboratory and Numerical Study of the Effect of Different Roughness of Side Walls and Bed on the Equivalent Roughness in a Compound Channel with Sloping Floodplains

Laboratory and Numerical Study of the Effect of Different Roughness of Side Walls and Bed on the Equivalent Roughness in a Compound Channel with Sloping Floodplains


Laboratory and Numerical Study of the Effect of Different Roughness of Side Walls and Bed on the Equivalent Roughness in a Compound Channel with Sloping Floodplains

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Laboratory and Numerical Study of the Effect of Different Roughness of Side Walls and Bed on the Equivalent Roughness in a Compound Channel with Sloping Floodplains

ارائه دهنده: Provider: Saidwali Baran

اساتید راهنما: Supervisors: Majid Fazli (Ph. D)

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees:

زمان و تاریخ ارائه: Time and date of presentation: 2021

مکان ارائه: Place of presentation:

چکیده: Abstract: The main purpose of the present research work is this to investigate the influence of different roughness of main channel and floodplain on the flow mechanism and equivalent roughness of the compound channel. Due to this different roughness cases of main channel and floodplain are investigated with different relative depth of flow. Distribution of streamwise velocity of flow in main channel and floodplains, average streamwise velocity of flow in overall experimental cross-section, secondary flow, boundary shear stress and force, equivalent roughness, and in the end the conveyance of the main channel and floodplain and also the overall conveyance of the compound channel are determined due to the different roughness cases. Modified Lotter, Horton, and Pavlovskii methods are used for determination of equivalent roughness and conveyance of the compound channel, to know which of the used methods is better for the compound channel which has lateral sloped floodplains. The results of the experiments show that the maximum streamwise velocity of flow occurs near the center of main channel and then again decreases in the centerline of main channel. Due to increasing the relative depth of flow the increasing rate of streamwise velocity in floodplain is higher than main channel. Wall roughness of floodplain has no important role on the compound channel flow. Also the conveyance of floodplain increases with the increase of main channel bed roughness. The overall conveyance of the compound channel decreases with the increases of particle size of surface roughening materials. And also the equivalent roughness of compound channel increases with increase of particle size of surface roughening materials. Bed roughness of main channel and floodplain and also the wall roughness of main channel have important role in decreasing the conveyance of the compound channel. The results also show that the Modified Lotter method is very suitable for determination the equivalent roughness coefficient of compound channel. Key Words: Compound Channel, Sloping Floodplains, Roughness, Equivalent Roughne

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