Search for dissertations about: "Absolute Convective Instabilities"

Found 5 swedish dissertations containing the words Absolute Convective Instabilities.

2. 1. The rotating-disk boundary-layer flow studied through numerical simulations

   Author : Ellinor Appelquist; Philipp Schlatter; Henrik Alfredsson; Rebecca Lingwood; Benoît Pier; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; laminar-turbulent transition; convective instability; absolute instability; crossflow instability; direct numerical simulations; Fysik; Physics;

   Abstract : This thesis deals with the instabilities of the incompressible boundary-layer flow thatis induced by a disk rotating in otherwise still fluid. The results presented include bothwork in the linear and nonlinear regime and are derived from direct numerical sim-ulations (DNS). READ MORE

4. 2. Direct numerical simulations of the rotating-disk boundary-layer flow

   Author : Ellinor Appelquist; Philipp Schlatter; Henrik Alfredsson; Rebecca Lingwood; Christopher Davies; KTH; []
   Keywords : Fluid mechanics; boundary layer; rotating disk; laminar-turbulent transition; convective instability; absolute instability; secondary instability; crossflow instability; direct numerical simulations; Teknisk mekanik; Engineering Mechanics;

   Abstract : This thesis deals with the instabilities of the incompressible boundary-layer flow that is induced by a disk rotating in otherwise still fluid. The results presented are mostly limited to linear instabilities derived from direct numerical simulations (DNS) but with the objective that further work will focus on the nonlinear regime, providing greater insights into the transition route to turbulence. READ MORE

5. 3. Feedback Control of Spatially Evolving Flows

   Author : Espen Åkervik; Dan Stefan Henningson; Luca Brandt; Martin Berggren; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Stability; Control; Estimation; Absolute Convective instabilities; Model reduction; Fluid mechanics; Strömningsmekanik;

   Abstract : In this thesis we apply linear feedback control to spatially evolving flows in order to minimize disturbance growth. The dynamics is assumed to be described by the linearized Navier--Stokes equations. Actuators and sensor are designed and a Kalman filtering technique is used to reconstruct the unknown flow state from noisy measurements. READ MORE

6. 4. Global stability and feedback control of boundary layer flows

   Author : Espen Åkervik; Dan S. Henningson; Luca Brandt; Dwight Barkley; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Stability; Global Stability; Feedback Control; Control; Estimation; Absolute Convective Instabilities; Model Reduction; Fluid mechanics; Strömningsmekanik;

   Abstract : In this thesis the stability of generic boundary layer flows is studied from a global viewpoint using optimization methods. Global eigenmodes of the incompressible linearized Navier-Stokes equations are computed using the Krylov subspace Arnoldi method. READ MORE

7. 5. Stability and transition in pitching wings

   Author : Prabal Negi; Dan Henningson; Ardeshir Hanifi; Philipp Schlatter; Olivier Marquet; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Flyg- och rymdteknik; Aerospace Engineering; Vehicle and Maritime Engineering; Farkostteknik;

   Abstract : The aeroelastic stability of airplanes is one of the most important aspects of airplane design. Flutter or divergence instabilities arising out of the interaction of fluid forces and structural elasticity must be avoided by design or through the limitation of the flight envelope. READ MORE