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Visar resultat 1 - 5 av 16 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Modelling of stably-stratified, convective and transitional atmospheric boundary layers using the explicit algebraic Reynolds-stress model

    Författare :Velibor Zeli; Gert Brethouwer; Arne V. Johansson; Stefan Wallin; Bert Holtslag; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; atmospheric turbulence; convective atmosphere; Reynolds-stress model; stably-stratified atmosphere; transitional atmosphere; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : The atmospheric boundary layer (ABL) is in continuous turbulent motion. The heating and cooling of the Earth’s surface drives mechanic and thermodynamic processes in the ABL through enhancing and damping of atmospheric turbulence. The surface forcing has a profound effect on the diurnal cycle of temperature,wind and related variables in the ABL. LÄS MER

  3. 2. Explicit algebraic subgrid-scale stress and passive scalar flux modeling in large eddy simulation

    Författare :Amin Rasam; Arne V. Johansson; Shia-Hui Peng; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; Large eddy simulation; explicit algebraic subgrid-scale model; passive scalar; stochastic modeling; backscatter; Fluid mechanics; Strömningsmekanik;

    Sammanfattning : The present thesis deals with a number of challenges in the field of large eddy simulation (LES). These include the performance of subgrid-scale (SGS) models at fairly high Reynolds numbers and coarse resolutions, passive scalar and stochastic modeling in LES. LÄS MER

  4. 3. Anisotropy-resolving subgrid-scale modelling using explicit algebraic closures for large eddy simulation

    Författare :Amin Rasam; Arne Johansson; Bernard Geurts; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; large eddy simulation; explicit algebraic subgridscale model; passive scalar; stochastic modelling; periodic hill flow; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : The present thesis deals with the development and performance analysis ofanisotropy-resolving models for the small, unresolved scales (”sub-grid scales”,SGS) in large eddy simulation (LES). The models are characterised by a descriptionof anisotropy by use of explicit algebraic models for both the subgridscale(SGS) stress tensor (EASSM) and SGS scalar flux vector (EASSFM). 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 modeling using automated code generation applied to asymmetric diffuser flow

    Författare :Johan Gullman-Strand; KTH; []
    Nyckelord :Fluid mechanics; Turbulence modeling; Explicit algebraic Reynolds stress model; Low-Re K-w; Automated code generation; Wall distance function;

    Sammanfattning : .... LÄS MER