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
Diplas, Panayiotis Committee Chair
Dancey, Clinton L. Committee Member
Loganathan, G. V. 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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