Search for dissertations about: "Tollmien-Schlichting waves"

Showing result 1 - 5 of 18 swedish dissertations containing the words Tollmien-Schlichting waves.

2. 1. Attenuation of boundary layer disturbances by means of streamwise vortices

   Author : Sohrab Sattarzadeh Shirvan; Jens H. M. Fransson; Valery Chernoray; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer stability; Tollmien-Schlichting waves; oblique waves; transition to turbulence; streamwise vortices; miniature vortex generators; instability control; drag reduction;

   Abstract : The stability of the boundary layer developed on a flat plate is studied in the presence of streamwise streaks where disturbances of different types are introduced in the wall-bounded shear layer. The experimental investigations are aimed at flow control by means of passively damping the energy growth of the disturbances in the streaky boundary layer and furthermore delay the onset of the transition in the streamwise direction. READ MORE

4. 2. Boundary layer streaks as a novel laminar flow control method

   Author : Sohrab Sattarzadeh Shirvan; Jens H. M. Fransson; Edward B. White; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer stability; laminar to turbulent transition; laminar flow control; drag reduction; Tollmien-Schlichting waves; oblique waves; streaky boundary layers; miniature vortex generators; discrete suction;

   Abstract : A novel laminar flow control based on generation of spanwise mean velocity gradients (SVG) in a flat plate boundary layer is investigated where disturbances of different types are introduced in the wall-bounded shear layer. The experimental investigations are aimed at; (i) generating stable and steady streamwise streaks in the boundary layer which set up spanwise gradients in the mean flow, and (ii) attenuating disturbance energy growth in the streaky boundary layers and hence delaying the onset of turbulence transition. READ MORE

5. 3. Stability analysis and transition prediction of wall-bounded flows

   Author : Ori Levin; KTH; []
   Keywords : Boundary layer; wall jet; algebraic growth; exponential growth; lift-up effect; streamwise streaks; Tollmien-Schlichting waves; free-stream turbulence; roughness element; transition prediction; Parabolized Stability Equations; Direct Numerical S;

   Abstract : Disturbances introduced in wall-bounded .ows can grow andlead to transition from laminar to turbulent .ow. In order toreduce losses or enhance mixing in energy systems, afundamental understanding of the . READ MORE

6. 4. Investigations of the asymptotic suction boundary layer

   Author : Jens H. M. Fransson; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Asymptotic suction boundary layer; Laminar-turbulent transition; Tollmien-Schlichting waves; Free stream turbulence; Engineering mechanics; Teknisk mekanik;

   Abstract : .... READ MORE

7. 5. Flow control of boundary lagers and wakes

   Author : Jens H. M. Fransson; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Laminar-turbulent transition; asymptotic suction boundary layer; free stream turbulence; Tollmien-Schlichting wave; stability; flow control; cylinder wake; Engineering mechanics; Teknisk mekanik;

   Abstract : Both experimental and theoretical studies have beenconsidered on flat plate boundary layers as well as on wakesbehind porous cylinders. The main thread in this work iscontrol, which is applied passively and actively on boundarylayers in order to inhibit or postpone transition toturbulence; and actively through the cylinder surface in orderto effect the wakecharacteristics. READ MORE