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Visar resultat 6 - 10 av 89 avhandlingar som matchar ovanstående sökkriterier.

  1. 6. Boundary Conditions for Spectral Simulations of Atmospheric Boundary Layers

    Författare :Erik Boström; Philipp Schlatter; Bernard J. Geurts; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : An atmospheric boundary layer (ABL) is generally a very high Reynolds number boundary layer over a fully rough surface that is influenced by different external forces. Numerical simulations of ABLs are typically demanding, particularly due to the high Reynolds numbers. LÄS MER

  3. 7. On the Arctic Boundary Layer : From Turbulence to Climate

    Författare :Thorsten Mauritsen; Gunilla Svensson; Joao Teixeira; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Atmospheric boundary layers; Turbulence; Stable stratification; Gravity waves; Mesoscale motion; Arctic climate; Meteorology; Meteorologi; atmosfärvetenskap; Atmospheric Sciences;

    Sammanfattning : The boundary layer is the part of the atmosphere that is in direct contact with the ground via turbulent motion. At mid-latitudes the boundary layer is usually one or a few kilometers deep, while in the Arctic it is much more shallow, typically a few hundred meters or less. LÄS MER

  4. 8. Global stability analysis of three-dimensional boundary layer flows

    Författare :Mattias Brynjell-Rahkola; Dan Henningson; Philipp Schlatter; Ardeshir Hanifi; Spencer Sherwin; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hydrodynamic stability; transition to turbulence; global analysis; boundary layers; roughness; laminar flow control; Stokes Laplace preconditioner; optimal forcing; crossflow vortices; Ginzburg-Landau; Falkner-Skan-Cooke; Blasius; lid-driven cavity;

    Sammanfattning : This thesis considers the stability and transition of incompressible boundary layers. In particular, the Falkner–Skan–Cooke boundary layer subject to a cylindrical surface roughness, and the Blasius boundary layer with applied localized suction are investigated. LÄS MER

  5. 9. On tribological design in gear tooth contacts

    Författare :Ellen Bergseth; Ulf Olofsson; Karsten Stahl; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; friction; gear contact; gear manufacturing; surface boundary layers; surface topography; wear;

    Sammanfattning : The correct tribological design will have a considerable effect on a gear’s service life and efficiency. The purpose of this thesis is to clarify the impact of variation in the gear tooth flank tribological system on the gear contact load capacity – to increase the understanding of how surface topography and lubricant interact. LÄS MER

  7. 10. Receptivity of Boundary Layers under Pressure Gradient

    Författare :Lars-Uve Schrader; Luca Brandt; Dan Henningson; Tamer Zaki; KTH; []
    Nyckelord :Leading-edge effects;

    Sammanfattning : Boundary-layer flow over bodies such as aircraft wings or turbine blades is characterized by a pressure gradient due to the curved surface of the body. The boundary layer may experience modal and non-modal instability, and the type of dominant instability depends on whether the body is swept with respect to the oncoming flow or not. LÄS MER