Sökning: "DNS"

Visar resultat 1 - 5 av 90 avhandlingar innehållade ordet DNS.

  1. 1. DNS and LES of Turbulent Natural Convection Boundary Layer

    Författare :Darioush Gohari Barhaghi; Chalmers University of Technology; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; DNS; free convection; LES; natural convection boundary layer; vertical cylinder;

    Sammanfattning : Turbulent natural convection boundary layers possess some special characteristicscompared to the other boundary layers.In order to study this kind of boundary layer, two powerful numerical methods,Direct Numerical Simulation or DNS and Large Eddy Simulation or LES,are used. LÄS MER

  2. 2. Combustion characteristics of some alternative fuels in ICE: : a detailed numerical study

    Författare :Siyuan Hu; Strömningsteknik; []
    Nyckelord :Combustion; duel fuel; methane; hydrogen; nheptane; methanol; DNS; simulation; openFoam; mixture-averaged; RCCI; ignition wave;

    Sammanfattning : Two major fuels commonly used in compression ignition (CI) and spark ignition (SI) enginesare diesel and gasoline. The reserve of diesel and gasoline is limited, however the combustion ofthese fuels giving rise to air pollution. LÄS MER

  3. 3. A Study of Turbulent Natural Convection Boundary Layers Using Large-Eddy Simulation

    Författare :Darioush Gohari Barhaghi; Chalmers University of Technology; []
    Nyckelord :natural convection boundary layer; DNS; LES; radiation heat transfer; free convection; cavity; vertical cylinder;

    Sammanfattning : The structure of turbulent natural convection boundary layers in differentgeometries and the effect of the buoyancy on a mixed convection boundarylayer are investigated. These geometries comprise a vertical finitecylinder, a vertical infinite channel, a cavity and a vertical finite channel. LÄS MER

  4. 4. Theoretical and numerical studies of sound propagation in low-Mach-number duct flows

    Författare :Chenyang Weng; Mats Åbom; Susann Boij; Ardeshir Hanifi; Anurag Agarwal; KTH; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aeroacoustics; Acoustic wave absorption; Acoustic wave propagation; Boundary layer turbulence; DNS; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : When sound waves propagate in a duct in the presence of turbulent flow, turbulent mixing can cause attenuation of the sound waves extra to that caused by the viscothermal effects. Experiments show that compared to the viscothermal effects, this turbulent absorption becomes the dominant contribution to the sound attenuation at sufficiently low frequencies. LÄS MER

  5. 5. Transition delay in boundary-layer flows via reactive control

    Författare :Nicolò Fabbiane; Dan S. Henningson; Shervin Bagheri; Denis Sipp; KTH; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; flow control; drag reduction; net energy saving; adaptive control; model-based control; optimal control; flat-plate boundary layer; laminar-to- turbulent transition; plasma actuator; direct numerical simulation; in-flight experiments; strömningsstyrning; friktionsreduktion; netto energibesparing; adaptiv styrning; modellbaserad styrning; optimal kontroll; gränsskikt öve en plan platta; laminärt till turbulent omslag; plasma aktuator; DNS; flyg prov; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : Transition delay in boundary-layer flows is achieved via reactive control of flow instabilities, i.e. Tollmien-Schlichting (TS) waves. Adaptive and model-based control techniques are investigated by means of direct numerical simulations (DNS) and experiments. LÄS MER