Sökning: "Gunilla Efraimsson"

Visar resultat 1 - 5 av 15 avhandlingar innehållade orden Gunilla Efraimsson.

  1. 1. Aerodynamics simulations of ground vehicles in unsteady crosswind

    Författare :Tristan Favre; Gunilla Efraimsson; Michael Leschziner; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Detached-Eddy Simulations; Crosswind; Aerodynamics; ;

    Sammanfattning : Ground vehicles, both on roads or on rail, are sensitive to crosswinds and the handling, travelling speeds or in some cases, safety can be affected. Full modelling of the crosswind stability of a vehicle is a demanding task as the nature of the disturbance, the wind gust, is complex and the aerodynamics, vehicle dynamics and driver reactions interact with each other. LÄS MER

  3. 2. Numerical Investigation of Unsteady Crosswind Aerodynamics for Ground Vehicles

    Författare :Tristan Favre; Gunilla Efraimsson; Mattias Chevalier; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aerodynamics; Vehicle Aerodynamics; Unsteady Aerodynamics; Crosswind; Unsteady Crosswind Aerodynamics; Detached-Eddy Simulations; DES; Vehicle engineering; Farkostteknik; Fluid mechanics; Strömningsmekanik;

    Sammanfattning : Ground vehicles are subjected to crosswind from various origins such as weather, topography of the ambient environment (land, forest, tunnels, high bushes...) or surrounding traffic. LÄS MER

  4. 3. Drag reduction using plasma actuators

    Författare :Romain Futrzynski; Gunilla Efraimsson; P. Henrik Alfredsson; Charles Mockett; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; flow control; drag reduction; plasma actuator; DMD; LES; optimization; pulsating flow; strömningskontroll; motståndsminskning; plasma ställdon; DMD; LES; optimering; pulserande flöde; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : This thesis is motivated by the application of active flow control on the cabin of trucks, thereby providing a new means of drag reduction. Particularly, the work presented strives to identify how plasma actuators can be used to reduce the drag caused by the detachment of the flow around the A-pillars. LÄS MER

  5. 4. Effect of drag reducing plasma actuators using LES

    Författare :Romain Futrzynski; Gunilla Efraimsson; P. Henrik Alfredsson; Emma Alenius; Johan Revstedt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; flow control; drag reduction; plasma actuator; DMD; LES; optimization; pulsating flow; strömningskontroll; motståndsminskning; plasmaaktuator; DMD; LES; optimering; pulserande strömning; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : The work performed in this thesis explores new ways of reducing the drag of ground vehicles. Specifically, the effect of plasma actuators are investigated numerically with the intention to delay separation around a half-cylinder, a geometry chosen to represent a simplified A-pillar of a truck. LÄS MER

  7. 5. Hybrid Methods for Unsteady Fluid Flow Problems in Complex Geometries

    Författare :Jing Gong; Jan Nordström; Gunilla Efraimsson; Mark H. Carpenter; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; hybrid methods; finite difference methods; finite volume methods; coupling procedure; stability; efficiency; artificial dissipation; Numerical analysis; Numerisk analys; Scientific Computing; Beräkningsvetenskap; Beräkningsvetenskap med inriktning mot numerisk analys;

    Sammanfattning : In this thesis, stable and efficient hybrid methods which combine high order finite difference methods and unstructured finite volume methods for time-dependent initial boundary value problems have been developed. The hybrid methods make it possible to combine the efficiency of the finite difference method and the flexibility of the finite volume method. LÄS MER