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Caltech Authors (167.915 recursos)

Repository of works by Caltech published authors.

Group = W. M. Keck Laboratory of Hydraulics and Water Resources

Mostrando recursos 1 - 20 de 22

  1. Stability of bottom armoring under the attack of solitary waves

    Naheer, Ehud
    An empirical relationship is presented for the incipient motion of bottom material under solitary waves. Two special cases of bottom material are considered: particles of arbitrary shape, and isolated sphere resting on top of a bed of tightly packed spheres. The amount of motion in the bed of particles of arbitrary shape is shown to depend on a dimensionless shear stress, similar to the Shields parameter. The mean resistance coefficient used in estimating this parameter is derived from considerations of energy dissipation, and is obtained from measurements of the attenuation of waves along a channel. A theoretical expression for the...

  2. Temperature effects in alluvial streams

    Taylor, Brent D.
    A laboratory investigation was conducted to determine the effects of water temperature on sediment discharge close to the bed (bed-load discharge), and on bed roughness and geometry in alluvial, open-channel flows. Three types of experiments were made: 1) Low-transport, flat-bed experiments in which all of the sediment discharged moved as bed load; 2) high-transport, flat-bed experiments with fine sands wherein there was considerable suspended sediment discharge; and 3) a series of experiments where the discharge was kept constant and the velocity varied to produce ripple, dune, and flat-bed configurations. The experiments were made in pairs. In each pair the velocity...

  3. Characteristics of transverse mixing in open-channel flows

    Okoye, Josephat K.
    The transverse spreading of a plume generated by a point source in a uniform open-channel flow is investigated. A neutrally-buoyant tracer was injected continuously at ambient velocity through a small round source at a point within the flow. Tracer concentration was measured in situ at several points downstream of the source using conductivity probes. Tracer concentration was analyzed in two phases. In Phase I, time-averaged concentration was evaluated, its distribution within the plume determined, and characteristic coefficients of transverse mixing calculated. It was shown that the transverse mixing coefficient varied with the flow level and was highest near the water...

  4. Effects of density differences on lateral mixing in open-channel flows

    Prych, Edmund A.
    This study investigates lateral mixing of tracer fluids in turbulent open-channel flows when the tracer and ambient fluids have different densities. Longitudinal dispersion in flows with longitudinal density gradients is investigated also. Lateral mixing was studied in a laboratory flume by introducing fluid tracers at the ambient flow velocity continuously and uniformly across a fraction of the flume width and over the entire depth of the ambient flow. Fluid samples were taken to obtain concentration distributions in cross-sections at various distances, x, downstream from the tracer source. The data were used to calculate variances of the lateral distributions of the...

  5. Hydraulic modeling of thermal outfall diffusers for the San Onofre nuclear power plant

    Koh, Robert C. Y.; Brooks, Norman H.; List, E. John; Wolanski, Eric J.
    Various hydraulic model tests were performed in connection with the design and performance of the offshore thermal outfalls for the San Onofre Nuclear Generating Station (jointly owned by the Southern California Edison Company and the San Diego Gas and Electric Company)near San Clemente, California. These include model investigations of: (i) the multiple port discharges for the proposed Units 2 and 3, (ii) the existing submerged single outlet from Unit 1, (iii) the discharge of heated water from the Units 2 and 3 intakes during heat treatment, and (iv) hydraulic characteristics of discharge ports. On the basis of these investigations, the...

  6. Motions of small boats moored in standing waves

    Raichlen, Frederic
    This study was conducted to determine the dynamic characteristics of small boats moored with non-linear-elastic lines in an asymmetrical manner. The motions being considered are surge motions where the moored boat is allowed to move either in the direction of the bow or the stern, but not in other coordinate directions. An analytical model is proposed where the small boat is simulated by a block-body which is moored asymmetrically to a fixed dock. A method is developed from which the non-linear restoring forces and the dynamic response of the boat in surge can be obtained. The restoring force which is...

  7. Tsunamis — A Model of Their Generation and Propagation

    Hammack, Joseph Leonard, Jr.
    A general solution is presented for water waves generated by an arbitrary movement of the bed (in space and time) in a two-dimensional fluid domain with a uniform depth. The integral solution which is developed is based on a linearized approximation to the complete (nonlinear) set of governing equations. The general solution is evaluated for the {specific case of a uniform upthrust or downthrow of a block section of the bed; two time-displacement histories of the bed movement are considered. An integral solution (based on a linear theory) is also developed for a three-dimensional fluid domain of uniform depth for a class of...

  8. Tsunamis -- the propagation of long waves onto a shelf

    Goring, Derek Garard
    The various aspects of the propagation of long waves onto a shelf (i.e., reflection, transmission and propagation on the shelf) are examined experimentally and theoretically. The results are applied to tsunamis propagating onto the continental shelf. A numerical method of solving the one-dimensional Boussinesq equations for constant depth using finite element techniques is presented. The method is extended to the case of an arbitrary variation in depth (i.e., gradually to abruptly varying depth) in the dirlection of wave propagation. The scheme is applied to the propagation of solitary waves over a slope onto a shelf and is confirmed by experiments. A theory is developed...

  9. Tsunamis -- the propagation of long waves onto a shelf

    Goring, Derek Garard
    The various aspects of the propagation of long waves onto a shelf (i.e., reflection, transmission and propagation on the shelf) are examined experimentally and theoretically. The results are applied to tsunamis propagating onto the continental shelf. A numerical method of solving the one-dimensional Boussinesq equations for constant depth using finite element techniques is presented. The method is extended to the case of an arbitrary variation in depth (i.e., gradually to abruptly varying depth) in the dirlection of wave propagation. The scheme is applied to the propagation of solitary waves over a slope onto a shelf and is confirmed by experiments. A theory is developed...

  10. Stationary waves and antidunes in alluvial channels

    Kennedy, John F. (John Fisher)
    A theoretical and laboratory investigation was made of antidunes and associated stationary waves. The objectives were to determine the factors involved in the formation of antidunes, the characteristics of the stationary waves, and the effects of antidunes and waves on the friction factor and sediment transport capacity of streams. In the potential flow solution for flow over a wavy bed it was hypothesized that the flow shapes the erodible sand bed by scour and deposition to conform to a streamline of the flow configuration for which the energy is a minimum. Under this hypothesis, flow over antidunes is the same as...

  11. Longitudinal dispersion in laboratory and natural streams

    Fischer, Hugo B.
    This study concerns the longitudinal dispersion of fluid particles which are initially distributed uniformly over one cross section of a uniform, steady, turbulent open channel flow. The primary focus is on developing a method to predict the rate of dispersion in a natural stream. Taylor's method of determining a dispersion coefficient, previously applied to flow in pipes and two-dimensional open channels, is extended to a class of three-dimensional flows which have large width-to-depth ratios, and in which the velocity varies continuously with lateral cross-sectional position. Most natural streams are included. The dispersion coefficient for a natural stream may be predicted from...

  12. Wave-induced oscillations of small moored vessels

    Raichlen, Fredric
    The general objective of this research is to investigate the motion of small boats moored to fixed or floating platforms in a standing wave environment. The study is directed toward an understanding of the problems of mooring small craft in marinas and toward providing information that will assist in the planning and operation of marinas. This report deals with the first phase of the experimental study concerning the surge motions of a simply moored body in a standing wave system. The body is a rectangular parallelpiped moored to a fixed support by means of a linear spring. In general it can be...

  13. Viscous stratified flow towards a line sink

    Koh, Robert C. Y.
    A theoretical and experimental investigation has been made for the problem of two-dimensional, viscous, incompressible, steady, slightly-stratified flow towards a line sink. The analytical solution was obtained from the Navier Stokes equations, the continuity equation, and the diffusion equation by making a boundary-layer-type assumption and by using a small perturbation technique based on a perturbation parameter proportional to the sink strength q. The effects of viscosity, diffusivity, and gravity have been included while the inertia effect is neglected in the zeroth order solution. The solution indicates that there exists a withdrawal layer which grows in thickness with the distance x...

  14. Vortex energy dissipator for San Diego ocean outfall – laboratory investigations

    Brooks, Norman H.; Blackmer, William H.
    The sewage effluent from the new sewage treatment plant for the City of San Diego, located on a bluff 95 feet above sea level on Point Lorna, is discharged to the ocean through a long submarine outfall pipe. Under almost all conditions of flow, the hydraulic head at the treatment plant exceeds that required for flow through the outfall. Therefore, the excess energy must be dissipated in a special hydraulic drop structure located on the shoreline between the treatment plant and the ocean outfall. The laboratory model investigation described herein basically sought to find a method for dissipating this excess energy...

  15. Exploratory studies of open-channel flow over laterally varying roughness

    Taylor, Robert Hugh
    An exploratory study was made of open-channel flow over beds consisting either entirely or partially of large granular roughness. Steady, uniform flow was established at various depths and velocities over two types of beds, one rough over the entire width of a laboratory flume, the other rough only over half the width and smooth over the other half. Friction factors were determined for these flows, and detailed velocity distributions were measured in three runs. The friction factors for the entirely rough beds compared closely with those predicted by the Karman-Prandtl equations, and the velocity distributions strongly suggested the existence of secondary...

  16. Further laboratory studies of the roughness and suspended load of alluvial streams

    Kennedy, J. F. (John Fisher)
    A laboratory study was made to determine the variation with depth and velocity of the hydraulic and sediment transport characteristics of a constant-discharge flow. Eight experimental runs were performed in a 60-foot long, 33.5-inch wide recirculating laboratory flume. The unit discharge for all runs was 0.50 cfs per ft. and the velocity was varied from 0.91 to 2.21 fps, corresponding to a change in depth from 0.550 to 0.228 ft. The bed sand used for these experiments had a geometric mean sieve diameter of 0.142 mm and a geometric standard deviation of 1.38. As the velocity was increased, the bed form...

  17. Studies on the mixing in a density-stratified shear flow

    Gartrell, Gregory, Jr.
    The objective of this study was to examine in a fundamental way the mixing processes in a stably-stratified shear flow. The results of the experimental program have yielded information on the nature of turbulence and mixing in density-stratified fluids. The results can be applied to such problems as the determination of the spreading and mixing rates of heated effluents discharged to lakes or the ocean, as well as to many geophysical problems. An experimental investigation was made to measure the mixing in a two-layered density-stratified shear flow in a flume 40-meters long, with a cross-section of 110 cm wide by 60...

  18. Wave induced oscillations in harbors of arbitrary shape

    Lee, Jiin-Jen
    Theoretical and experimental studies were conducted to investigate the wave induced oscillations in an arbitrary shaped harbor with constant depth which is connected to the open-sea. A theory termed the "arbitrary shaped harbor" theory is developed. The solution of the Helmholtz equation, ∇^2f + k^af = 0, is formulated as an integral equation; an approximate method is employed to solve the integral equation by converting it to a matrix equation. The final solution is obtained by equating, at the harbor entrance, the wave amplitude and its normal derivative obtained from the solutions for the regions outside and inside the harbor. Two...

  19. Lecture notes on sediment transportation and channel stability

    Vanoni, Vito A.; Brooks, Norman H.; Kennedy, John F. (John Fisher)
    These notes have been prepared for a series of lectures on sediment transportation and channel stability given by the authors to a group of engineers and geologists of the U. S. Department of Agriculture assembled at Caltech on September 12-16,1960. The material herein is not intended to serve as a complete textbook, because it covers only subjects of the one-week sequence of lectures Due to limitation of space and time, coverage of many subjects is brief and others are omitted altogether. At the end of each chapter the reader will find a selected list of references for more detailed study.

  20. Numerical solutions of turbulent buoyant jet problems

    Fan, Loh-Nien; Brooks, Norman H.
    Theoretical solutions were obtained for four classes of turbulent buoyant jet problems, namely, 1) an inclined, round buoyant jet in a stagnant, uniform ambient fluid; 2) an inclined, round buoyant jet in a stagnant ambient fluid with linear density-stratification; 3) an inclined, slot buoyant jet in a stagnant, uniform ambient fluid; 4) an inclined, slot buoyant jet in a stagnant ambient fluid with linear density-stratification. This report is a summary of the numerical simulations on buoyant jets in stagnant environments carried out in connection with previous investigations by Fan (10), Fan and Brooks (12) and Brooks and Koh (8). Using the integral type of analysis,...

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