Sökning: "Vorticity"

Visar resultat 11 - 15 av 45 avhandlingar innehållade ordet Vorticity.

  1. 11. Development of Separation Phenomena on a Passenger Car

    Författare :Sabine Bonitz; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; complex flows; vortex formation; vehicle aerodynamics; flow separation; limiting streamlines; crossflow separation;

    Sammanfattning : The general shape of a vehicle influences its aerodynamic performance through separation phenomena and flow structure development. Since these flow characteristics have a direct influence on the energy efficiency, safety and comfort, it is essential to study their formation and evolution into the freestream. LÄS MER

  3. 12. Receptivity of Boundary-Layer Flows over Flat and Curved Walls

    Författare :Lars-Uve Schrader; Luca Brandt; Dan Stefan Henningson; Gregoire Casalis; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Boundary-layer receptivity; laminar-turbulent transition; swept-plate boundary layer; Görtler flow; leading-edge effects; swept-wing flow; crossflow vortices; Görtler rolls; disturbance streaks; wall roughness; free-stream turbulence; Fluid mechanics; Strömningsmekanik;

    Sammanfattning : Direct numerical simulations of the receptivity and instability of boundary layers on flat and curved surfaces are herein reported. Various flow models are considered with the aim to capture aspects of flows over straight and swept wings such as wall curvature, pressure variations, leading-edge effects, streamline curvature and crossflow. LÄS MER

  4. 13. Large Eddy Simulation of Non-Local Turbulence and Integral Measures of Atmospheric Boundary Layers

    Författare :Igor Esau; Frans Nieuwstadt; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Meteorology; Planetary boundary layers; large eddy simulations; non-local turbulence; Meteorologi; Meteorology; Meteorologi; Meteorology; meteorologi;

    Sammanfattning : A new large eddy simulation (LES) code is developed and used to investigate non-local features of turbulent planetary boundary layers (PBLs). The LES code is based on filtered Navier-Stokes equations, which describe motions of incompressible, Boussinesq fluid at high Reynolds numbers. LÄS MER

  5. 14. Wave interactions by Hamiltonian methods

    Författare :Krister Wiklund; Umeå universitet; []
    Nyckelord :Hamiltonian formulation; wave interaction; stability; variational principles;

    Sammanfattning : This thesis is devoted to the description of fluids and gases from a Hamiltonian point of view. The method we apply is a development of the theory invented by Hamilton (1805-1865). The original formulation is restricted to a certain family of dynamical variables; the canonical variables. LÄS MER

  7. 15. Non-reflecting Boundary Conditions for Wave Propagation Problems

    Författare :Daniel Appelö; KTH; []
    Nyckelord :;

    Sammanfattning : We consider two aspects of non-reflecting boundaryconditions for wave propagation problems. First we evaluate aproposed Perfectly Matched Layer (PML) method for thesimulation of advective acoustics. It is shown that theproposed PML becomes unstable for a certain combination ofparameters. A stabilizing procedure is proposed andimplemented. LÄS MER