Prediction of Velocity and Boundary Shear Stress Distributions in Non-Prismatic Compound Channels with Converging Floodplains by Using LES Model

Prediction of Velocity and Boundary Shear Stress Distributions in Non-Prismatic Compound Channels with Converging Floodplains by Using LES Model


Prediction of Velocity and Boundary Shear Stress Distributions in Non-Prismatic Compound Channels with Converging Floodplains by Using LES Model

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Prediction of Velocity and Boundary Shear Stress Distributions in Non-Prismatic Compound Channels with Converging Floodplains by Using LES Model

ارائه دهنده: Provider: Marjan Monadi

اساتید راهنما: Supervisors: Jalal Sadeghian (PhD) - Bahram Rezaei (PhD)

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees:

زمان و تاریخ ارائه: Time and date of presentation: March, 09, 2020

مکان ارائه: Place of presentation:

چکیده: Abstract: One of the important aspects of river hydraulics is the transverse velocity distribution and shear shear stresses of the rivers. The rivers appear to be in the form of a cross section at their extreme ends, so that during the flood, water flows through the main channel of the river and enters the floodplains. The floodplain has always been considered for various recreational, commercial, agricultural and residential areas due to its proximity to the river bank and its high latitude and fertile soil. Therefore, the awareness of the hydraulic flow in the floodplain is essential for the protection of human beings as well as the structures and facilities existing therein. In this study, the shear stresses in the main channel bed and floodplain and the average depth velocity distribution in the convergent compound channel with the convergence lengths of 2 and 6 meters and the relative depths of 0.3, 0.4 and 0.5 by using Ansys Fluent software and It is modeled using the Large eddy simulation (LES) and compared with laboratory results. The compound channel modeling in this study consists of a main channel with a width of 400 mm and a depth of 50 mm, and floodplains with a width of 400 mm. The results of the study of predicting the accuracy of the average depth velocity and shear stress in different sections of the channel using the LES model showed that the percentage of the relative error of the mean of its permissible value was 15% lower in all sections of the channel and the results Modeling is within the allowed error range defined for numerical models. Also, the LES model has a very high accuracy of data prediction and is suitable for numerical simulation of flow in compound channels and is capable of modeling the turbulent current in a convergent compound channel with high precision. The results showed that with increasing relative depth of channel in the channel due to increasing turbulence the measurement accuracy increased. It also increases accuracy as the flow progresses due to the convergence of the current and the increased perturbation. Key Words: Nonprismatic compound channel, Convergence floodplain, Ansys-Fluent, LES, Compound Channel

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