Sökning: "Turbulent exchange"

Visar resultat 11 - 15 av 25 avhandlingar innehållade orden Turbulent exchange.

1. 11. High-Performance Finite Element Methods : with Application to Simulation of Diffusion MRI and Vertical Axis Wind Turbines

   Författare :Van-Dang Nguyen; Johan Hoffman; Johan Jansson; Axel Målqvist; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; High performance finite element method; computational diffusion MRI; turbulent flow; vertical axis wind turbine.; Computer Science; Datalogi;

   Sammanfattning : The finite element methods (FEM) have been developed over decades, and together with the growth of computer engineering, they become more and more important in solving large-scale problems in science and industry. The objective of this thesis is to develop high-performance finite element methods (HP-FEM), with two main applications in mind: computational diffusion magnetic resonance imaging (MRI), and simulation of the turbulent flow past a vertical axis wind turbine (VAWT). LÄS MER

3. 12. Modeling Auto-Ignition, Flame Propagation and Combustion in Non-Stationary Turbulent Sprays

   Författare :Anders Karlsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; auto-ignition; transient; flame propagation; turbulence; spray formation; prediction; stirred reactor approximation; model; reduced chemistry; combustion;

   Sammanfattning : This thesis focuses on detailed numerical studies of spray formation, auto-ignition, envelope flame development and combustion in a simple two-dimensional axi-symmetric geometry. A Lagrangian -- Eulerian formulation is used to analyze the droplet motion and gas flow field. LÄS MER

4. 13. Implementation and Analysis of Air-Sea Exchange Processes in Atmosphere and Ocean Modelling

   Författare :Björn Carlsson; Anna Rutgersson; Ann-Sofi Smedman; Öyvind Saetra; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sensible heat flux; Latent heat flux; Momentum flux; Wind stress; Marine boundary layer; Air–Sea interaction; Swell; Climate model; Ocean model; Roughness parameter; Drag coefficient; Wave breaking; Meteorology; Meteorologi;

   Sammanfattning : To understand and to predict the weather and climate, numerical models are important tools and it is crucial that the controlling processes are described correctly. Since 70% of the global surface is covered with water the description how the ocean and atmosphere communicates has a considerable impact. LÄS MER

5. 14. Uncovering Ocean Mixing near Rough Bathymetry : Using Broadband Acoustics

   Författare :Julia C. Muchowski; Christian Stranne; Martin Jakobsson; Lars Umlauf; Lars Arneborg; Fer Ilker; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ocean mixing; diapycnal mixing; broadband acoustics; turbulence microstructure; rough bathymetry; stratified flow over obstacles; observations of turbulent mixing; Baltic Sea research; maringeologi; Marine Geology;

   Sammanfattning : Ocean mixing related to rough bathymetry is highly dynamic and exhibits large spatial and temporal variability. Therefore, established in-situ methods as well as numerical models often lack the resolution to capture this type of mixing. In this thesis, acoustics are used to observe, map and quantify stratified mixing at unprecedented resolution. LÄS MER

7. 15. Estimating the Air-Water Gas Transfer Velocity during Low Wind Conditions

   Författare :Sam Fredriksson; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Air.sea gas exchange; Turbulence; Heat flux; Natural convection; Shear; Direct numerical simulations; Gas transfer velocity; IR; Flux-chambers;

   Sammanfattning : The abundances of atmospheric carbon dioxide, CO2, and methane, CH4, are increasing. These increases affect e.g., the global carbon cycle and the climate both regionally and globally. LÄS MER