NUMERICAL INVESTIGATION ON THE RELATIVE IMPORTANCE OF PARAMETERS INFLUENCING THE AIR-WATER INTERFACE OF A STABLE HYDRAULIC JUMP

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Willats, E. (2019). NUMERICAL INVESTIGATION ON THE RELATIVE IMPORTANCE OF PARAMETERS INFLUENCING THE AIR-WATER INTERFACE OF A STABLE HYDRAULIC JUMP. Unc Charlotte Electronic Theses And Dissertations.
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Abstract

Simulations were undertaken with a commercial Finite Volume ComputationalFluid Mechanics code, Star-CCM+, in order to predict macroscopic and internalflow features of a steady hydraulic jump at a Froude number Fr =5.8. This workwas carried out using an Unsteady Reynolds-Averaged-Navier-Stokes approach in a2D framework that utilized the Realizable k-e turbulence model. The air-waterinteractions were modeled with the volume of fluid method, of which the specificimplementation included high resolution interface construction approach. Numericalexperiments were carried out first investigating the influence of computational parameterson the veracity of CFD predictions, and a set of these variables were identifiedthat produces results with high experimental correlation. The results include, amongothers, the location of the free surface and the tail water depth of the hydraulic jumpwhich show excellent agreement with experimental values. The volume fraction of airwas predicted at stream-wise distances of 8.33d1 and 12.5d1 from the toe of the jump,where d1 is the upstream flow depth just prior to the hydraulic jump. These predictionswere made correctly in both the advective-shear region and the roller region at8.33d1 from the toe, but were over predicted at 12.5d1.A two-level four-factor full factorial design was also made of selected parametersthat govern the behavior of the free surface: sharpening factor, interface momentumdissipation, the courant number, and surface tension. The dependent variables forthis analysis were the volume fraction of air in the advective-shear region, volumefraction of air in the roller region, and the bottom shear stress. The results of linearregression quantified for the first time the relative importance of these four factors onengineering quantities of interest which are critical for the design of hydraulic structures. Specifically, the regression analysis indicates that the parameter of sharpeningfactor has at least twice the impact of the next nearest factor on the three engineeringquantities of interest, and thus it becomes paramount that this parameter governingthe air-water interface be selected with care.

Details
Author

Willats, Ethan

Title

NUMERICAL INVESTIGATION ON THE RELATIVE IMPORTANCE OF PARAMETERS INFLUENCING THE AIR-WATER INTERFACE OF A STABLE HYDRAULIC JUMP

Physical Description

1 online resource (105 pages) : PDF

Date

2019

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

Simulations were undertaken with a commercial Finite Volume ComputationalFluid Mechanics code, Star-CCM+, in order to predict macroscopic and internalflow features of a steady hydraulic jump at a Froude number Fr =5.8. This workwas carried out using an Unsteady Reynolds-Averaged-Navier-Stokes approach in a2D framework that utilized the Realizable k-e turbulence model. The air-waterinteractions were modeled with the volume of fluid method, of which the specificimplementation included high resolution interface construction approach. Numericalexperiments were carried out first investigating the influence of computational parameterson the veracity of CFD predictions, and a set of these variables were identifiedthat produces results with high experimental correlation. The results include, amongothers, the location of the free surface and the tail water depth of the hydraulic jumpwhich show excellent agreement with experimental values. The volume fraction of airwas predicted at stream-wise distances of 8.33d1 and 12.5d1 from the toe of the jump,where d1 is the upstream flow depth just prior to the hydraulic jump. These predictionswere made correctly in both the advective-shear region and the roller region at8.33d1 from the toe, but were over predicted at 12.5d1.A two-level four-factor full factorial design was also made of selected parametersthat govern the behavior of the free surface: sharpening factor, interface momentumdissipation, the courant number, and surface tension. The dependent variables forthis analysis were the volume fraction of air in the advective-shear region, volumefraction of air in the roller region, and the bottom shear stress. The results of linearregression quantified for the first time the relative importance of these four factors onengineering quantities of interest which are critical for the design of hydraulic structures. Specifically, the regression analysis indicates that the parameter of sharpeningfactor has at least twice the impact of the next nearest factor on the three engineeringquantities of interest, and thus it becomes paramount that this parameter governingthe air-water interface be selected with care.

Genre

masters theses

Subjects--Topics

Hydraulic engineering

Degree

M.S.

Keywords

Design of Experiments
Hydraulic Jump
Volume of Fluid

Subject Area

Mechanical Engineering

Advisor(s)

Uddin, Mesbah

Committee Members

Bowen, James
Keanini, Russell

Degree Note

Thesis (M.S.)--University of North Carolina at Charlotte, 2019.

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Rights Holder Information

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Identifier

Willats_uncc_0694N_12130

Permalink

http://hdl.handle.net/20.500.13093/etd:2439