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Caltech Authors (147.820 recursos)

Repository of works by Caltech published authors.

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

Mostrando recursos 1 - 20 de 71

  1. Wave uplift pressures on horizontal platforms

    French, Jonathan A.
    The major objective of the study has been to investigate in detail the rapidly-varying peak uplift pressure and the slowly-varying positive and negative uplift pressures that are known to be exerted by waves against the underside of a horizontal pier or platform located above the still water level, but not higher than the crests of the incident waves. In a "two-dimensional" laboratory study conducted in a 100-ft long by 15-in.-wide by 2-ft-deep wave tank with a horizontal smooth bottom, individually generated solitary waves struck a rigid, fixed, horizontal platform extending the width of the tank. Pressure transducers were mounted flush with the smooth soffit, or underside, of the platform. The location...

  2. Contributions to the Question of a Velocity Formula and Roughness Data for Streams, Channels and Closed Pipelines

    Strickler, A.
    This widely referenced, but seldom seen report is of both historic and engineering interest. While much of the work presented has since been eclipsed by more recent work, the velocity equation for open channels (Eq. 37) is still in use. It is interesting to learn how this equation came into being, particularly in light of the fact that it predates the well known von Karman-Prandtl logarithmic velocity distribution equation. Also of interest, is the plethora of velocity equations for open channels and pipes, which existed over sixty years ago (particularly when one considers that the search for a satisfactory equation continues to this day). A final benefit of this...

  3. Matching the refractive index [in] density stratified flows

    Hannoun, Imad
    The use of optical methods such as Laser Doppler Velocimetry (LDV) and laser induced fluorescence techniques (LIF) in experimental fluid mechanics is becoming very common. The greatest advantage of such methods is that measurements are made without disturbing the flow. A major impediment to using optical methods to study density stratified flows is the variation of the refractive index within the flow field. McDougall (1979a) has proposed a method for the reduction of refractive index variations while maintaining a density difference. The method relies on the fact that various solutes in, say, water can contribute to the density and to the refractive index of the solution in different proportions. A...

  4. Sediment studies in the Brazilian Amazon River Basin

    Vanoni, Vito A.
    The work was to be carried out as part of WMO's participation in the United Nations Development Project (UNDP) on Hydrology and Climatology of the Brazilian Amazon River Basin under the direction of Eduardo Basso, Project Manager. This project is carried out in cooperation with The General Directorate for Amazon Development of the Brazilian Government (SUDAM).

  5. Surface chemical and physical behavior of chrysotile asbestos in natural waters and water treatment

    Bales, Roger C.
    Chrysotile asbestos fibers enter California waters from physical weathering of magnesium-silicate, serpentine rocks in mountains of the northern and central portions of the state. Chrysotile particles, initially positively charged below pH 8.9 because of their magnesium-hydroxide surface, become negatively charged due to dissolution and adsorption of organic matter. Chrysotile suspended in 0.1 M inorganic electrolyte at pH 7-10 for up to five days dissolves with magnesium being released in excess of the 3:2 Mg:Si to silica molar ratio in the solid. The rate of magnesium release exhibits a fractional dependence on hydrogen-ion concentration: r = k_1'[H^+]^(0.24) The observed rate constant,...

  6. The reduction and dissolution of Mn(III) and Mn(IV) oxides by organics

    Stone, Alan Thomas
    Although it is known that manganese oxides are solubilized by reduction in anoxic waters, the chemical processes are poorly understood. A study of the reduction and dissolution of manganese oxide suspensions by twenty-seven organic substrates that have chemical structures similar to those of natural organics was undertaken to determine the rates and mechanisms of the solubilization reactions. Dissolution of suspensions by hydroquinone in the pH range 6.5 < pH < 8.5 is described by the following experimental rate law: d[Mn^(2+)]/dt = k_l{H^+}^(0. 46) [HQ]^(1.0) (Mn_T - [Mn^(2+)]) where [Mn^(2+)] is the amount of dissolved manganese, [HQ] is the hydroquinone concentration,...

  7. Turbulence and turbulent transport in sediment-laden open-channel flows

    Lyn, Dennis Anthony
    Some aspects of turbulence in sediment-laden open-channel flows are examined. A conceptual model based on similarity hypotheses rather than the traditional mixing-length closures is proposed. It is argued that, over a wide range of laboratory conditions, the main effect of the suspended sediment on the flow is confined to a layer near the bed. If such a distinct layer can be discerned, then this is separated from the outer flow by an inertial subregion in which the mean-velocity profile is approximately logarithmic, with an associated von Kàrman constant of ≈ 0.4, i.e., the same value as in single-phase flows. It...

  8. Particle collisions and coalescence in fluids

    Valioulis, Iraklis Anestis
    Coagulation, in the physical context, is looked upon here first from the fundamental perspective of collision and coalescence of individual particles. A Monte Carlo technique is used to investigate the particle size distribution in a suspension of coagulating particles when one or more collision mechanisms operate. The effect of interparticle forces - hydrodynamic, van der Waals' and electrostatic - on the collision probability of the particles is examined. The results obtained are used to evaluate the well-known dynamic equilibrium hypothesis according to which an equilibrium particle size distribution is assumed to exist under the action of a given collision mechanism....

  9. 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...

  10. A study of the entrainment and turbulence in a plane buoyant jet

    Kotsovinos, Nikolas E.
    The entrainment and mixing processes in a two-dimensional vertical turbulent buoyant (heated) jet in its transition state from a pure jet to a pure plume have been studied. The ambient fluid is of uniform density and non-flowing except for the flow induced by the jet. Density variations are assumed small. The equations of motion integrated across the jet have been carefully examined and it has been found that the kinematic buoyancy flux of a heated plume and the kinematic momentum flux of a pure jet are not in general conserved. It has been proven that the flow in a two-dimensional...

  11. Interpretations of results from hydraulic modeling of thermal outfall diffusers for the San Onofre Nuclear Power Plant

    List, E. J.; Koh, R. C. Y.
    This report presents and interpretation of results obtained during the hydraulic model study previously documented in "Hydraulic Modeling of Thermal Outfall Diffusers for the San Onofre Nuclear Power Plant" which described the hydraulic laboratory studies conducted to investigate outfall configurations for the thermal discharge from proposed Units 2 and 3 at the San Onofre Nuclear Generating Station, jointly owned by the Southern California Edison Company and San Diego Gas and Electric Company. A number of different experimental investigations were performed to develop the conceptual design for the new Units 2 and 3 discharge diffusers. The primary reason for the investigations...

  12. 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...

  13. 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...

  14. Mixing of density-stratified impoundments with buoyant jets

    Ditmars, John D.
    This study is an investigation of the mixing of density-stratified impoundments by means of buoyant jets created by a pumping system. The deterioration of water quality which often occurs in density-stratified lakes and reservoirs may be counteracted by mixing. The physical aspects of the mixing process are the primary concern of this study, although several implications regarding changes in water quality are indicated. A simulation technique is developed to predict the time-history of changes in the density-depth profiles of an impoundment during mixing. The simulation model considers the impoundment closed to all external influences except those due to the pumping...

  15. 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...

  16. Laboratory design-studies of the effect of waves on a proposed island site for a combined nuclear power and desalting plant

    Vanoni, Vito; Raichlen, Frederic
    There were four major objectives to this investigation: 1) the determination of the degree of stability of the island face when constructed of armor units of various weights; 2) the run-up for a two-dimensional wave system impinging on the island face; 3) the run-up envelope on the four sides of the island in a three-dimensional model; and 4) the wave patterns caused by the effect of the island on its wave environment. Models having three different length scales were tested in the wave tank (1:50, 1:45, and 1:40) and these models are referred to as the two-dimensional models. One model...

  17. 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...

  18. Coagulation in continuous particle size distributions; theory and experimental verification

    Hunt, James Robert
    Previous theories for particle coagulation are not readily applicable to the continuous particle size distributions encountered in natural waters. By extending concepts developed in the analysis of aerosol dynamics, predictions of continuous particle size distributions were obtained dimensionally for size intervals dominated by Brownian, shear, differential sedimentation coagulation and gravitational settling. A dynamic steady state size distribution was assumed to exist, maintained by a constant flux of particle volume through the distribution. Predictions have been successfully compared with the shapes of particle size distributions measured in oceanic waters. An experimental program was designed to test the predictions with cleaned clay...

  19. Mathematical model for multiple cooling tower plumes

    Wu, Frank H. Y.; Koh, Robert C. Y.
    A mathematical model is developed resulting in a computer program for the prediction of the behavior of plumes from multiple cooling towers with multiple cells. A general integral method based on the conservation of mass, momentum, energy (heat), and moisture fluxes (before and after plume merging), were employed in the prediction scheme. The effects of ambient stratifications of temperature, moisture, and wind are incorporated in the model. An axisymmetric round plume is assumed to be emitted from each individual cell before interference with neighboring plumes. A finite length slot plume in the central part and two half round plumes at...

  20. Dispersion in hydrologic and coastal environments

    Brooks, Norman H.
    This report summarizes the results of a five-year laboratory research project on various flow phenomena of importance to transport and dispersion of pollutants in hydrologic and coastal environments. The results are useful in two general ways: first, to facilitate the prediction of ambient water quality from effluent characteristics in various water environments; and secondly, to provide the basis for design of systems (like outfalls) required to meet given ambient water quality requirements. The results for buoyant jets may be used for the design of waste-water outfalls in oceans, reservoirs, lakes, and large estuaries. Particular emphasis is given to line sources...

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