Numerical Analysis of the Energy Dissipation due to Hydraulic Jump in an Inclined Open Channel Flow

Cheah, Yuen Kei (2021) Numerical Analysis of the Energy Dissipation due to Hydraulic Jump in an Inclined Open Channel Flow. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Open channel flow is characterized by a free surface which is exposed to the atmosphere. In an open channel flow, the Froude number is important in describing the flow regime. When the flow reaches supercritical state, the high kinetic energy in the flow has the ability in causing adverse effect on the channel bed and hydraulic structures. To overcome this problem, a considerable amount of the kinetic energy in the supercritical flow can be dissipated by utilizing hydraulic jump. The hydraulic jump in an open channel flow with various approach Froude numbers ranging from 4.5 to 9.0 and degree of inclinations ranging from -10° to 5° is simulated by using ANSYS (FLUENT). Before proceeding with the numerical simulation, mesh convergence study is conducted to determine the optimum mesh size that provides the most accurate results with the lowest computational cost. Model validation is also conducted simultaneously with the sensitivity analysis of the turbulence models in order to determine the turbulence model that is able to achieve the most accurate result. The significant parameters of the hydraulic jump such as the sequent depth ratio, length of the hydraulic jump and energy dissipated by the hydraulic jump were studied. The relationship between the approach Froude number and the degree of inclination of the flume with the sequent depth ratio, energy dissipation and length of the jump is investigated and it is found that the optimum approach Froude number and degree of inclination of the flume that results in the highest relative energy loss is the combination of 5° of inclination with approach Froude number of 6.8 which results in around 76% efficiency.