Sökning: "Boundary Effects"

Visar resultat 1 - 5 av 433 avhandlingar innehållade orden Boundary Effects.

  1. 1. Simulations of turbulent boundary layers with suction and pressure gradients

    Författare :Alexandra Bobke; Philipp Schlatter; Ramis Örlü; Ayse Gul Gungor; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layers; near-wall turbulence; history effects; asymptotic suction boundary layers; large-eddy simulation;

    Sammanfattning : The focus of the present licentiate thesis is on the effect of suction and pressure gradients on turbulent boundary-layer flows, which are investigated separately through performing numerical simulations.The first part aims at assessing history and development effects on adverse pressure-gradient (APG) turbulent boundary layers (TBL). LÄS MER

  3. 2. CFD Methods for Predicting Aircraft Scaling Effects

    Författare :Karl Pettersson; Arthur Rizzi; Bryan Richards; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; CFD; Scaling Effects; Boundary Layer Transition; Preconditioning; Vehicle engineering; Farkostteknik;

    Sammanfattning : This thesis deals with the problems of scaling aerodynamic data from wind tunnel to free flight  conditions. The main challenges when this scaling should be performed is how the model support, wall interference and the potentially lower Reynolds number in the windtunnel should be corrected. LÄS MER

  4. 3. Numerical Studies of Wall Effects of Laminar Flames

    Författare :Johan Andrae; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wall effects; laminar premixed flames; Chemkin; boundary layer flow; Chemical engineering; Kemiteknik;

    Sammanfattning : Numerical simulations have been done with the CHEMKINsoftware to study different aspects of wall effects in thecombustion of lean, laminar and premixed flames in anaxisymmetric boundary-layer flow. The importance of the chemical wall effects compared to thethermal wall effects caused by the development of the thermaland velocity boundary layer has been investigated in thereaction zone by using different wall boundary conditions, walltemperatures and fuel/air ratios. LÄS MER

  5. 4. Receptivity of Boundary-Layer Flows over Flat and Curved Walls

    Författare :Lars-Uve Schrader; Luca Brandt; Dan Stefan Henningson; Gregoire Casalis; KTH; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  7. 5. Boundary integral methods for Stokes flow : Quadrature techniques and fast Ewald methods

    Författare :Oana Marin; Anna-Karin Tornberg; Anita Layton; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; boundary integral; Stokes flow; quadrature rule; Ewald decomposition;

    Sammanfattning : Fluid phenomena dominated by viscous effects can, in many cases, be modeled by the Stokes equations. The boundary integral form of the Stokes equations reduces the number of degrees of freedom in a numerical discretization by reformulating the three-dimensional problem to two-dimensional integral equations to be discretized over the boundaries of the domain. LÄS MER