Search for dissertations about: "vorticity stretching"

Found 4 swedish dissertations containing the words vorticity stretching.

  2. 1. Spectral-element simulations of turbulent wall-bounded flows including transition and separation

    Author : Johan Malm; Dan Henningson; Philipp Schlatter; Suad Jakirlic; KTH; []
    Keywords : spectral-element method; direct numerical simulation DNS ; large-eddy simulation LES ; turbulence; transition; over-integration; three-dimensional separation; massively parallel simulations; proper orthogonal decomposition POD ; Koopman modes; vorticity stretching; coherence; SRA - E-vetenskap SeRC ; SRA - E-Science SeRC ;

    Abstract : The spectral-element method (SEM) is used to study wall-bounded turbulent flowsin moderately complex geometries. The first part of the thesis is devoted to simulations of canonical flow cases, such as temporal K-type transitionand turbulent channel flow, to investigate general resolution requirements and computational efficiency of the numerical code nek5000. READ MORE

  4. 2. Receptivity of Boundary-Layer Flows over Flat and Curved Walls

    Author : Lars-Uve Schrader; Luca Brandt; Dan Stefan Henningson; Gregoire Casalis; KTH; []
    Keywords : 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;

    Abstract : 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. READ MORE

  5. 3. Experimental studies of turbulent boundary layer separation and control

    Author : Kristian Angele; KTH; []
    Keywords : turbulence; boundary layer; separition; adverse pressure graddient;

    Abstract : The object ofthe present work is to experimentally study thecase ofa turbulent boundary layer subjected to an AdversePressure Gradient (APG) with separation and reattachment. Thisconstitutes a good test case for advanced turbulence modeling. READ MORE

  6. 4. Investigation of jet pulsation effects on near-nozzle mixing and entrainment

    Author : Alexander Nygård; Laszlo Fuchs; Lisa Prahl Wittberg; Mireia Altimira; Xandra Margot; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sprays; Nozzle; Mixing; Pulsation; Engineering Mechanics; Teknisk mekanik;

    Abstract : Turbulent jet flows are very common in engineering applications. One example is that of fuel injection in internal combustion engines, which is closely related to the combustion process. Because of the widespread use, the resulting emissions of such engines have a significant impact on human health and the environment. READ MORE