Sökning: "stabilitet"

Visar resultat 16 - 20 av 336 avhandlingar innehållade ordet stabilitet.

  1. 16. Transition to turbulence in the asymptotic suction boundary layer

    Författare :Taras Khapko; Dan Henningson; Philipp Schlatter; Yohann Duguet; Marc Avila; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layers; instability; laminar-turbulent transition; dynamical systems; edge states; near-wall turbulence; laminarisation;

    Sammanfattning : The focus of this thesis is on the numerical study of subcritical transition to turbulence in the asymptotic suction boundary layer (ASBL). Applying constant homogeneous suction prevents the spatial growth of the boundary layer, granting access to the asymptotic dynamics. LÄS MER

  3. 17. Wind turbine simulations using spectral elements

    Författare :Elektra Kleusberg; Dan Henningson; Philipp Schlatter; Stefan Ivanell; Johan Meyers; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wind turbine; wakes; wake interaction; computational fluid dynamics; actuator line method; spectral elements; free-stream turbulence; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : Understanding the flow around wind turbines is a highly relevant research question due to the increased interest in harvesting energy from renewable sources. This thesis approaches the topic by means of numerical simulations using the actuator line method and the incompressible Navier–Stokes equations in the spectral element code Nek5000. LÄS MER

  4. 18. Wind-turbine wakes - Effects of yaw, shear and turbine interaction

    Författare :Elektra Kleusberg; Dan Henningson; Philipp Schlatter; Stefan Ivanell; Johan Meyers; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wind-turbine wakes; yaw; tip-vortex breakdown; shear; computational fluid dynamics; actuator-line method; spectral-element method; Vindturbinsvakar; girning; turbulent nedbrott hos spetsvirvlar; skjuvning; vakinteraktion; beräkningsströmningsdynamik; actuator line-metod; spektralelementmetod; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : The actuator-line method is used together with the incompressible Navier–Stokes equations to investigate the flow development behind wind turbines. Initial investigations focus on providing a thorough validation of the implementation in the spectral-element flow solver Nek5000 against existing numerical and experimental datasets. LÄS MER

  5. 19. Stability analysis of channel flow laden with small particles

    Författare :Joy Klinkenberg; Luca Brandt; Cristian Marchioli; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Transition; modal analysis; non-modal analysis; Direct Numerical Simulations; multi-phase flow; heavy particles; light particles; particle-laden;

    Sammanfattning : This thesis deals with the stability of particle laden flows. Both modal and non-modal linear analyses have been performed on two-way coupled particleladen flows, where particles are considered spherical, solid and either heavy or light. When heavy particles are considered, only Stokes drag is used as interaction term. LÄS MER

  7. 20. Transition in Particle-laden Flows

    Författare :Joy Klinkenberg; Luca Brandt; Shuisheng He; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Transition; modal analysis; non-modal analysis; multi-phase flow; particle-laden; heavy particles; light particles;

    Sammanfattning : This thesis presents the study of laminar to turbulent transition of particle laden flows. When a flow becomes turbulent, the drag increases one order of magnitude compared to a laminar flow, therefore, much research is devoted to understand and influence the transition. LÄS MER