Sökning: "homogeneous turbulence"

Visar resultat 6 - 10 av 50 avhandlingar innehållade orden homogeneous turbulence.

1. 6. Mean Wind and Turbulence Conditions in the Boundary Layer above Forests

   Författare :Johan Arnqvist; Hans Bergström; Anna Rutgersson; Stefan Söderberg; Søren Larsen; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Wind power; Forest; Turbulence; Waves; Spectra; Wind model; Atmospheric stability; Vindkraft; Skog; Turbulens; Vågor; Spektra; Modell; Atmosfärisk stabilitet;

   Sammanfattning : As wind turbines have grown, new installation areas become possible. Placing wind turbines in forested landscapes introduce uncertainties to the wind resource estimation. LÄS MER

3. 7. Subgrid-scale modelling for large-eddy simulation including scalar mixing in rotating turbulent shear flows

   Författare :Linus Marstorp; Arne Johansson; Lars-Erik Eriksson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; large-eddy simulation; subgrid-scale model; Fluid mechanics; Strömningsmekanik;

   Sammanfattning : The aim of the present study is to develop subgrid-scale models that are relevant for complex flows and combustion. A stochastic model based on a stochastic Smagorinsky constant with adjustable variance and time scale is proposed. LÄS MER

4. 8. Suspensions of finite-size rigid particles in laminar and turbulent flows

   Författare :Walter Fornari; Luca Brandt; Jérémie Bec; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Suspensions; complex fluids; sedimentation; rheology; turbulence;

   Sammanfattning : Dispersed multiphase flows occur in many biological, engineering and geophysical applications. Understanding the behavior of suspensions is a difficult task. In the present work, we numerically study the behavior of suspensions of finite-size rigid particles in different flows. LÄS MER

5. 9. Development of Numerical Methods for Accurate and Efficient Scale-Resolving Simulations

   Författare :Magnus Carlsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; High-order gradient reconstruction; Hybrid RANS-LES; Scale-resolving simulation; Synthetic Turbulence; Numerical methods; Turbulence modelling;

   Sammanfattning : Hybrid RANS (Reynolds-Averaged Navier-Stokes)-LES (Large-Eddy Simulation) techniques are considered to be sufficiently accurate and computationally affordable for the aeronautical industry. Scale-resolving simulations is a powerful tool that can accurately predict complex unsteady compressible high-Reynolds-number turbulent flows, as often encountered aeronautical applications. LÄS MER

7. 10. Spark Assisted Compression Ignition, SACI

   Författare :Håkan Persson; Förbränningsmotorer; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; flame propagation; PLIF; LDV; chemiluminescence imaging; residuals; negative valve overlap; low temperature combustion; SACI; spark assistance; HCCI; turbulence; charge stratification; cycle to cycle;

   Sammanfattning : The strong focus on decreasing carbon dioxide emissions due to limited natural resources of fossil fuel as well as alarming climate changes drives the research and development of our prime mover, the combustion engine, faster then ever. The minimum requirement is a power source with increased efficiency while emitting ultra low levels of hazardous local and regional emissions. LÄS MER