Search for dissertations about: "Boundary-layer receptivity"

Showing result 1 - 5 of 16 swedish dissertations containing the words Boundary-layer receptivity.

2. 1. On stability and receptivity of boundary-layer flows

   Author : Nima Shahriari; Ardeshir Hanifi; Dan S. Henningson; Peter J. Schmid; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer receptivity; acoustic receptivity; swept-wing flow; crossflow vortices; roughness element; global stability analysis; direct numerical simulation; plasma actuator; Engineering Mechanics; Teknisk mekanik;

   Abstract : This work is concerned with stability and receptivity analysis as well as studies on control of the laminar-turbulent transition in boundary-layer flows through direct numerical simulations. Various flow configurations are considered to address flow around straight and swept wings. 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. Study of generation, growth and breakdown of streamwise streaks in a Blasius boundary layer

   Author : Luca Brandt; KTH; []
   Keywords : Fluid mechanics; laminar-turbulent transition; boundary layer flow; transient growth; streamwise streaks; lift-up effect; receptivity; free-stream turbulence; streak instability; secondary instability; Direct Numerical Simulation.;

   Abstract : Transition from laminar to turbulent flow has beentraditionally studied in terms of exponentially growingeigensolutions to the linearized disturbance equations.However, experimental findings show that transition may occuralso for parameters combinations such that these eigensolutionsare damped. READ MORE

6. 4. Numerical studies of bypass transition in the Blasius boundary layer

   Author : Luca Brandt; KTH; []
   Keywords : Fluid Mechanics; laminar-turbulent transition; boundary layer flow; transient growth; streamwise streaks; secondary instability;

   Abstract : Experimental findings show that transition from laminar toturbulent ow may occur also if the exponentially growingperturbations, eigensolutions to the linearised disturbanceequations, are damped. An alternative non-modal growthmechanism has been recently identi fied, also based on thelinear approximation. READ MORE

7. 5. 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