Sökning: "Turbulens"

Visar resultat 1 - 5 av 60 avhandlingar innehållade ordet Turbulens.

  1. 1. Modelling the early to mid-Holocene Arctic climate

    Författare :Marit Berger; Arne Johansson; Rodrigo Caballero; KTH; []
    Nyckelord :Arctic; early Holocene; mid-Holocene; climate modelling; paleoclimate; sea ice; climate change;

    Sammanfattning : In the recent past it has become evident that the Earth's climate is changing, and that human activity play a significant role in these changes. One of the regions where the ongoing climate change has been most evident is in the Arctic: the surface temperature has increased twice as much in this region as compared to the global average, in addition, a significant decline in the Arctic sea-ice extent has been observed in the past decades. LÄS MER

  3. 2. Direct Numerical Simulation of Boundary-layer Transition with Free-stream Turbulence

    Författare :Kristina Durovic; Dan Henningson; Ardeshir Hanifi; Philipp Schlatter; Tamer Zaki; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : This thesis considers the generation and influence of free-stream turbulence toboundary layer transition on both flat and curved bodies in the flow. Variousflow configurations such as flow around the flat plate with a sharp leading edgeand low-pressure turbine blades are considered. LÄS MER

  4. 3. Turbulence modeling of compressible flows with large density variation

    Författare :Igor Grigoriev; Arne Johansson; Stefan Wallin; Geert Brethouwer; Stefan Hickel; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; DRSM; EARSM; active scalar; compressible flow; reacting flow; supercritical flow; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : In this study we highlight the influence of mean dilatation and mean density gradient on the Reynolds stress modeling of compressible, heat-releasing and supercritical turbulent flows.Firstly, the modeling of the rapid pressure-strain correlation has been extended to self-consistently account for the influence of mean dilatation. LÄS MER

  5. 4. Explicit algebraic turbulence modelling in buoyancy-affected shear flows

    Författare :Werner Lazeroms; Arne Johansson; Antti Hellsten; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Turbulent flows affected by buoyancy forces occur in a large amount of applica-tions, from heat transfer in industrial settings to the effects of stratification inEarth’s atmosphere. The two-way coupling between the Reynolds stresses andthe turbulent heat flux present in these flows poses a challenge in the searchfor an appropriate turbulence model. LÄS MER

  7. 5. Turbulence modelling applied to the atmospheric boundary layer

    Författare :Werner Lazeroms; Arne Johansson; Geert Brethouwer; Evgeni Fedorovich; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; turbulence; RANS models; explicit algebraic Reynolds-stress models; buoyancy; stable stratification; thermal convection; atmospheric boundary layer;

    Sammanfattning : Turbulent flows affected by buoyancy lie at the basis of many applications, both within engineering and the atmospheric sciences. A prominent example of such an application is the atmospheric boundary layer, the lowest layer of the atmosphere, in which many physical processes are heavily influenced by both stably stratified and convective turbulent transport. LÄS MER