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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Measurements on turbulent compressible boundary layer properties in pressure gradients.

Brakmann, Georg. January 1971 (has links)
No description available.
52

A contribution to the study of uniformly diverging and converging turbulent boundary layers /

Crabbe, R S January 1977 (has links)
No description available.
53

Contributions to laminar boundary layer theory for gases /

Thurston, R. N. January 1952 (has links)
No description available.
54

On the stability of the supersonic boundary layer /

Elsharnoby, Mohamed A. January 1987 (has links)
No description available.
55

Investigation of the effects of electrostatic fields on heat transfer and boundary layers /

Velkoff, Henry René January 1962 (has links)
No description available.
56

Boundary layer characteristics in a diverging duct /

Bubb, James Edward January 1966 (has links)
No description available.
57

Investigation of the pressure distribution on a blunt-fin blunt-plate combination at a Mach number of 11.26 /

Thomas, John Powers January 1966 (has links)
No description available.
58

A preliminary analytical and experimental investigation of helicopter rotor boundary layers /

Blaser, Dwight A. January 1971 (has links)
No description available.
59

Numerical investigation of transition control of a flat plate boundary layer.

Kral, Linda Dee. January 1988 (has links)
A numerical model has been developed for investigating boundary layer transition control for a three-dimensional flat plate boundary layer. Control of a periodically forced boundary layer in an incompressible fluid is studied using surface heating techniques. The spatially evolving boundary layer is simulated. The Navier-Stokes and energy equations are integrated using a fully implicit finite difference/spectral method. The Navier-Stokes equations are in vorticity-velocity form and are coupled with the energy equation through the viscosity dependence on temperature. Both passive and active methods of control by surface heating are investigated. In passive methods of control, wall heating is employed to alter the stability characteristics of the mean flow. Both uniform and nonuniform surface temperature distributions are studied. In the active control investigations, temperature perturbations are introduced locally along finite heater strips to directly attenuate the instability waves in the flow. A feedback control loop is employed in which a downstream sensor is used to monitor wall shear stress fluctuations. Passive control of small amplitude two-dimensional Tollmien-Schlichting waves and three-dimensional oblique waves are numerically simulated with both uniform and nonuniform passive heating applied. Strong reductions in both amplitude levels and amplification rates are achieved. Active control of small amplitude two-dimensional and three-dimensional disturbances is also numerically simulated. With proper phase control, in phase reinforcement and out of phase attenuation is demonstrated. A receptivity study is performed to study how localized temperature perturbations are generated into Tollmien-Schlichting waves. It is shown that narrow heater strips are more receptive in that they maximize the amplitude level of the disturbances in the flow. It is also found that the local temperature fluctuations cause mainly a strong normal gradient in spanwise vorticity. Control of the early stages of the nonlinear breakdown process is also investigated. Uniform passive control is applied to both the fundamental and sub-harmonic routes to turbulence. A strong reduction in amplitude levels and growth rates results. In particular, the three-dimensional growth rates are significantly reduced below the uncontrolled levels. Active control of the fundamental breakdown process is also numerically simulated. Control is achieved using either a two-dimensional or three-dimensional control input.
60

Langmuir circulations in a coastal environment during CBLAST

Elge, Murat 09 1900 (has links)
Approved for public release; distribution is unlimited / Langmuir circulations in a coastal environment at an inner shelf site with strong tidal forcing were examined using a 4-month observation of high-resolution velocity profiles during the ONR-sponsored CBLAST-Low air-sea interaction experiment. Because of their potential contributions to mixing processes in the surface boundary layer, Langmuir circulations are important for naval operations such as ASW, MCM and Amphibious operations in littoral waters. A detection algorithm for upwelling / downwelling velocities due to Langmuir circulations was developed. Analyses focused on long-fetch, unstratified water column conditions with locally developed seas. The observations showed that strong Langmuir circulations greatly reduced water column shear arising from the tidally forced bottom boundary layer, while there was no significant effect from the strong tidal boundary layer on the formation of Langmuir cells. Long fetch conditions had the strongest vertical velocities with Langmuir number 0.1-0.4, while short fetch conditions have weaker vertical velocities with Langmuir number greater than 0.5. Cell vertical velocities were correlated with the water friction velocity, but penetration depths did not depend on forcing mechanisms. Spacing and penetration depths were correlated for increasing wind speed and wave heights whereas this correlation was not seen for constant high wind speed and wave heights. / Lieutenant Junior Grade, Turkish Navy

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