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Showing result 1 - 5 of 18 essays matching the above criteria.

  1. 1. Focal Spot Optimization Using Spatial Light Modulation and a Phase Retrieval Algorithm

    University essay from Lunds universitet/Atomfysik; Lunds universitet/Fysiska institutionen

    Author : Robert Petersen; [2023]
    Keywords : Spatial Light Modulation; Phase Retrieval Algorithm; Focal Spot Optimization; Adaptive Optics; Wavefront Sensing; Lasers; Physics and Astronomy; Technology and Engineering;

    Abstract : Aberrations to the wavefront of a laser beam reduce the quality of the focal spot and are generally undesired. This project is aimed at determining the aberrations of laser beams by using a phase retrieval algorithm and to show that it is possible to correct the aberrations with a spatial light modulator to optimize the focal spot. READ MORE

  3. 2. Computational Fluid Dynamics of the flow in a diffuser : - like geometry

    University essay from KTH/Skolan för teknikvetenskap (SCI)

    Author : Rasmus Johansson Oskarsson; [2023]
    Keywords : Fluid mechanics; Flow simulation; RANS; Flow separation; Diffuser;

    Abstract : Simulations were performed to investigate flow separation of an asymmetricdiffuser - like geometry. The geometry used for the simulations was modeledafter an experimental setup with recorded flow data, which was compared tothe simulated data. For all simulations, steady state flow at the inlet was usedwith the assumption of a 2D flow. READ MORE

  4. 3. Implementing spatial variance in the rate of photolytic breakdown of NO2 in urban street canyons

    University essay from Lunds universitet/Institutionen för energivetenskaper

    Author : Fabian Friberg; [2022]
    Keywords : cfd; computational fluid dynamics; NOx; street canyon; NO2; NO; O3; photolysis; OpenFOAM; Physics and Astronomy;

    Abstract : In this study a module for calculating the solar exposure of individual fluid cells was developed to more accurately represent the effect of photolysis on the pollutant dispersion in an urban street canyon. The module was tested and validated on 12 different cases, each with a different geographical location, time of year and/or time of day. READ MORE

  5. 4. Turbulence Intensity During Low-Level Jets in the Baltic Sea

    University essay from Uppsala universitet/Luft-, vatten- och landskapslära

    Author : Thomasson August; [2021]
    Keywords : Low-Level Jet; Turbulence intensity; Shear sheltering; LiDAR; Baltic Sea; Low-Level Jet; Turbulensintesitet; Shear sheltering; LiDAR; Östersjön;

    Abstract : Low-level jets (LLJs) are local wind speed maximums in the atmospheric boundary layer. In the Baltic Sea, LLJs are frequently occurring in spring and summer. It is an important phenomena to consider for wind energy parks, and changes in turbulence during the jets can effect the efficiency of said parks. READ MORE

  6. 5. Deep learning for non-intrusive sensing in turbulence with passive scalars

    University essay from KTH/Strömningsmekanik och Teknisk Akustik

    Author : Arivazhagan Geetha Balasubramanian; [2021]
    Keywords : Turbulent boundary layer; passive scalar; direct numerical simulation; Prandtl number; Machine learning; convolutional neural network; Turbulent gränsskikt; passiv skalär; direkt numerisk simulering; Prandtl-nummer; maskininlärning; faltningsneurala nätverk;

    Abstract : The near-wall modelling of turbulent flows has been an active field of research due to the computational cost associated with the direct numerical simulations of such flow, which are characterized by a wide range of length and time scales. With the recent advancements in technological capabilities, the availability of high-fidelity data has enabled the construction of data-driven approaches to model turbulence. READ MORE