Sökning: "Turbulence"

Visar resultat 6 - 10 av 699 avhandlingar innehållade ordet Turbulence.

1. 6. Optical Turbulence Characterization for Ground-Based Astronomy

   Författare :Susanna Hagelin; Anna Rutgersson; Elena Masciadri; Valentina Zitelli; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; site testing; atmospheric effects; turbulence; optical turbulence; applied meteorology; mesoscale models; Meteorology; Meteorologi; Astronomy and astrophysics; Astronomi och astrofysik; Meteorologi; Meteorology;

   Sammanfattning : The optical turbulence, which creates perturbations of the wavefronts coming from the stars, is caused by small-scale fluctuations in the index of refraction of the atmosphere and is a problem for astronomers because it limits the maximum resolution of the ground-based telescopes. One way of identifying the best sites to build astronomical observatories, where the influence of the optical turbulence is as small as possible, is to use the standard meteorological parameters to get a first idea of the potential of a site. LÄS MER

3. 7. Turbulence modulation effects caused by small droplets using one-dimensional-turbulence

   Författare :Marco Fistler; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Multiphase Flow; Droplets; one-dimensional-turbulence ODT ; Turbulence;

   Sammanfattning : This thesis presents a stochastic model to study turbulence modulation effects on gas phases caused by small droplets or more generally speaking particles to achieve a better understanding about the physics and with the aim to provide data for a subgrid-scale (SGS) model for Large-eddy-simulations. The one-dimensional-turbulence (ODT) model addresses one of the major issues for multiphase flow simulations, namely computational costs. LÄS MER

4. 8. Droplet growth in atmospheric turbulence : A direct numerical simulation study

   Författare :Xiang-Yu (李翔宇) Li; Gunilla Svensson; Axel Brandenburg; Wojciech Grabowski; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; cloud micro-physics; turbulence; inertial particles; DNS; condensation; collision; coalescence; atmosfärvetenskap och oceanografi; Atmospheric Sciences and Oceanography;

   Sammanfattning : This Ph.D. thesis examines the challenging problem of how turbulence affects the growth of cloud droplets in warm clouds. Droplets grow by either condensation or collision. LÄS MER

5. 9. Statistical characteristics of two-dimensional and quasigeostrophic turbulence

   Författare :Andreas Vallgren; Erik Lindborg; Johan Nilsson; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; two-dimensional turbulence; decaying turbulence; quasigeostrophic turbulence; direct numerical simulation DNS ; coherent vortices; energy cas- cade; enstrophy cascade; intermittency; massively parallel simulations; Non-linear dynamics; chaos; Icke-linjär dynamik; kaos;

   Sammanfattning : Two codes have been developed and implemented for use on massively parallelsuper computers to simulate two-dimensional and quasigeostrophic turbulence.The codes have been found to scale well with increasing resolution and width ofthe simulations. LÄS MER

7. 10. On stability, transition and turbulence in three-dimensional boundary-layer flows

   Författare :Seyed Mohammd Hosseini; Ardeshir Hanifi; Spencer Sherwin; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Receptivity; stability; optimal growth; three-dimensional bound- ary layers; crossflow instability; roughness control; freestream turbulence; sec- ondary instability; transition; turbulence;

   Sammanfattning : A lot has changed since that day on December 17, 1903 when the Wright brothers made the first powered manned flight. Even though the concepts behind flying are unaltered, appearance of stat-of-the-art modern aircrafts has undergone a massive evolution. LÄS MER