Title page for ETD etd-011999-232112

Type of Document

Master's Thesis

Author

Kanellopoulos, Paul M.

URN

etd-011999-232112

Title

Incipient Motion Under Shallow Flow Conditions

Degree

Master of Science

Department

Civil Engineering

Advisory Committee

Advisor Name	Title
Dr. Panayiotis Diplas	Committee Chair
Dr. Clinton Dancey	Committee Member
Dr. G.V. Loganathan	Committee Member

Keywords

Probability of Entrainment
Rough Walls
Surface Waves
Shallow Flows
Threshold Conditions
Relative Depth
Mountain Rivers

Date of Defense

1998-12-16

Availability

unrestricted

Abstract

Laboratory experiments were conducted to investigate the effect of low relative depth
and high Froude number on the dimensionless critical shear stress (Shields parameter).
Spherical particles of four different densities and an 8mm diameter were used as movable test
material. The relative depth ranged from 2 to 12 and the Froude number ranged from 0.36 to 1.29.
The results show that the traditional Shields diagram cannot be used to predict the incipient
motion of coarse sediment particles when the relative depth is below 10 and the Froude number
is above 0.5, approximately. Experiments using glass balls, whose density is almost identical
to that of natural gravel, show that the Shields parameter can be twice as large in shallow flows
than in deep flows. The results also show that the Shields parameter is dependent on the density
of the particles. Data obtained from other studies support the findings of the present work.
These findings can result in significant cost savings for riprap.
Additionally, velocity profiles using a laser-Doppler velocimeter (LDV) were taken for
the glass ball incipient motion experiments. The purpose of this was to study possible changes in
the velocity distribution with decreasing relative depth and increasing Froude number.
The results show that the von Karman and integral constants in the law of the wall do not change
in the range of relative depths and Froude numbers tested.

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