Search for dissertations about: "Turbulent spots"

Showing result 1 - 5 of 7 swedish dissertations containing the words Turbulent spots.

  2. 1. Numerical studies of transtion in wall-bounded flows

    Author : Ori Levin; Dan Henningson; Nikolaus Adams; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer; suction; wall jet; streaks; waves; periodic disturbance; localized disturbance; turbulent spot; algebraic growth; exponential growth; stability; transition thresholds; transition prediction; PSE; DNS; Fluid mechanics; Strömningsmekanik;

    Abstract : Disturbances introduced in wall-bounded flows can grow and lead to transition from laminar to turbulent flow. In order to reduce losses or enhance mixing in energy systems, a fundamental understanding of the flow stability and transition mechanism is important. READ MORE

  4. 2. Edge states and transition to turbulence in boundary layers

    Author : Taras Khapko; Dan Henningson; Philipp Schlatter; Yohann Duguet; Rich Kerswell; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer; transition to turbulence; direct numerical simulation; edge state; free-stream turbulence; bypass transition; probabilistic cellular automaton; turbulence at the onset; laminar–turbulent coexistence; laminarisation; Engineering Mechanics; Teknisk mekanik;

    Abstract : The focus of this thesis is the numerical study of subcritical transition to turbulence in boundary-layer flows. For the most part, boundary layers with uniform suction are considered. Constant homogeneous suction counteracts the spatial growth of the boundary layer, rendering the flow parallel. READ MORE

  5. 3. Formation of solar bipolar regions : Magnetic flux concentrations from suction of the negative effective magnetic pressure instability

    Author : Illa Rivero Losada; Axel Brandenburg; Matthias Rempel; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Magnetohydrodynamics MHD ; turbulence; dynamo; Sun: magnetic fields; Sun: rotation; Sun: activity; Sun: dynamo; Astronomy; astronomi;

    Abstract : Sunspots stand out on the visible solar surface. They appear as dark structures evolving and changing over time. They host energetic and violent events, like coronal mass ejections and flares, and concentrate strong magnetic fields. READ MORE

  6. 4. Optimisation and control of shear flows

    Author : Antonios Monokrousos; Dan S. Henningson; Laurette Tuckerman; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; shear flows; flow control; optimal disturbances; Lagrange method; transition to turbulence; non-linear dynamics; Engineering mechanics; Teknisk mekanik;

    Abstract : Transition to turbulence and flow control are studied by means of numerical simulations for different simple shear flows. Linear and non-linear optimisation methods using the Lagrange multiplier technique are employed. READ MORE

  7. 5. Noise radiation from drill steels : and other experimental investigations in acoustics and fluid mechanics

    Author : Jan-Erik Ögren; Luleå tekniska universitet; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Strömningslära; Fluid Mechanics;

    Abstract : Drill rod noise has become a major noise source in percussive drilling. Generation of flexural waves, which seem to be responsible for most of the noise, is studied in a model with dynamic photoelasticity and in the real drill rod with strain gauge technique. READ MORE