Browsing by Author "KENNEDY, JF"

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MOMENT MODEL OF NONUNIFORM CHANNEL-BEND FLOW .1. FIXED-BEDS
(1993-07-01)
YEH, KC
;
KENNEDY, JF
;
交大名義發表
;
土木工程學系
;
National Chiao Tung University
A nonuniform, fixed-boundary, channel-bend flow is formulated as two coupled sets of equations, each comprising two simultaneous equations, derived from the cross-section-integrated equations (in circular cylindrical coordinates) of conservation of flux of moment of momentum, and the depth-integrated momentum and continuity equations. Boundary shear stresses are related to the primary-flow shear stress and the primary and secondary velocities. The equations are solved numerically and the results found to be in satisfactory agreement with experimental data. The moment formulation elucidates the interplay among the secondary and primary flows, notably the observed flattening of primary velocity profiles, over-shoot of the secondary flow, radial redistribution of the depth-averaged primary velocity, and the secondary translational velocity. The erodible-bed case is treated in the companion paper.
MOMENT MODEL OF NONUNIFORM CHANNEL-BEND FLOW .2. ERODIBLE BEDS
(1993-07-01)
YEH, KC
;
KENNEDY, JF
;
交大名義發表
;
土木工程學系
;
National Chiao Tung University
The hybrid integral-differential moment and momentum model of fixed-boundary channel-bend flows developed in the companion paper is extended to erodible-bed flows. The theta unit sediment discharge is formulated as a power of local depth-averaged theta velocity; and the r unit sediment discharge as proportional to the ratio of the excess of the r bed shear stress, over the radial component of the submerged weight of the sediment bed layer, to the theta bed shear stress. Bed topography is computed from two-dimensional (2D) sediment continuity. The resulting two coupled sets of simultaneous equations are solved numerically. The model yields accurate predictions of the velocities (primary and secondary), and 2D bed topography. The average radial bed slope, primary velocity-profile exponent, and secondary rotational and translational velocities exhibit much larger variations along the channel than in fixed-boundary bends. The increased variation and oscillatory behavior of these quantities are elucidated from moment-of-momentum conservation and interaction of bed topography and flow.