Sökning: "flat-plate boundary layer"

Visar resultat 16 - 20 av 38 avhandlingar innehållade orden flat-plate boundary layer.

1. 16. Studies of the rotating-disk boundary-layer flow

   Författare :Shintaro Imayama; Henrik Alfredsson; Rebecca Lingwood; Peter Thomas; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fluid mechanics; laminar-turbulent transition; convective instability; absolute instability; secondary instability; hot-wire anemometry; Teknisk mekanik; Engineering Mechanics;

   Sammanfattning : The rotating-disk boundary layer is not only a simpler model for the study of cross-flow instability than swept-wing boundary layers but also a useful simplification of many industrial-flow applications where rotating configurations are present. For the rotating disk, it has been suggested that a local absolute instability, leading to a global instability, is responsible for the small variation in the observed laminar-turbulent transition Reynolds number however the exact nature of the transition is still not fully understood. LÄS MER

3. 17. Semi-Toeplitz preconditioning for linearized boundary layer problems

   Författare :Samuel Sundberg; Lina von Sydow; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Numerical Analysis; Numerisk analys;

   Sammanfattning : We have defined and analyzed a semi-Toeplitz preconditioner for time-dependent and steady-state convection-diffusion problems. Analytic expressions for the eigenvalues of the preconditioned systems are obtained. LÄS MER

4. 18. Flow control of boundary lagers and wakes

   Författare :Jens H. M. Fransson; KTH; []
   Nyckelord :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;

   Sammanfattning : 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. LÄS MER

5. 19. Receptivity of crossflow-dominated boundary layers

   Författare :David Tempelmann; Ardeshir Hanifi; Dan Henningson; Anatoli Tumin; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Receptivity; three-dimensional boundary layers; optimal growth; adjoint solutions; swept wing;

   Sammanfattning : This thesis deals with receptivity mechanisms of three-dimensional, crossflow-dominated boundary layers. The receptivity of two model problems, a swept-flat-plate and a swept-wing boundary layer, is investigated by solving the parabolised stability equations (PSE) as well as by performing direct numerical simulations (DNS). LÄS MER

7. 20. Laninar-turbulent boundary layer transition influenced by free stream turbulence

   Författare :Jonas Westin; KTH; []
   Nyckelord :;

   Sammanfattning : Laminar-turbulent transition in a flat plate boundary layerhas been considered, with a special emphasis on the influencefrom free stream turbulence (FST)First, experiments on linear stability ofTollmien-Schlichting (TS) waves in a Blasius boundary layer wasstudied. This is a well-known example from hydrodynamicstability theory, which has hitherto suffered from unresolveddiscrepancies between experiments and linear theory. LÄS MER