Sökning: "localized roughness"

Visar resultat 1 - 5 av 10 avhandlingar innehållade orden localized roughness.

  1. 1. Studies on instability and optimal forcing of incompressible flows

    Författare :Mattias Brynjell-Rahkola; Dan S. Henningson; Ardeshir Hanifi; Philipp Schlatter; François Gallaire; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; hydrodynamic stability; optimal forcing; resolvent operator; Laplace preconditioner; spectral element method; eigenvalue problems; inverse power method; direct numerical simulations; Falkner–Skan–Cooke boundary layer; localized roughness; crossflow vortices; Blasius boundary layer; localized suction; helical vortices; lid-driven cavity; cylinder flow; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : This thesis considers the hydrodynamic instability and optimal forcing of a number of incompressible flow cases. In the first part, the instabilities of three problems that are of great interest in energy and aerospace applications are studied, namely a Blasius boundary layer subject to localized wall-suction, a Falkner–Skan–Cooke boundary layer with a localized surface roughness, and a pair of helical vortices. LÄS MER

  3. 2. Topographical Impact on Space Charge Injection, Accumulation and Breakdown in Polymeric HVDC Cable Interfaces

    Författare :Espen Doedens; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; interfaces; XLPE; roughness; cable peelings; polymer surfaces; space charge; field enhancement factor; PEA; DC breakdown; extruded cable; roughness enhanced charge injection; HVDC; charge injection;

    Sammanfattning : Extruded HVDC cable systems feature a variety of interface types, for which physio-chemical properties will depend on the type of application. Such applications can be joints, terminations or the cable itself, all introducing different material combinations and manufacturing methods. LÄS MER

  4. 3. Characterization of Different Interface Types for HVDC Extruded Cable Applications

    Författare :Espen Doedens; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; polymer surfaces; cable peelings; HVDC; Roughness; Charge injection; XLPE; Field enhancement factors; Schottky injection; DC breakdown; Voltage decay; interfaces; Fowler-Nordheim injection; extruded cable; Roughness assisted charge injection.; Charge decay;

    Sammanfattning : In extruded HVDC cable systems a variety of interface types can be found, and the interfacial properties depend on the application within the system. Such applications can be joints, terminations or the cable itself and they will all have different material combinations and manufacturing methods. LÄS MER

  5. 4. Global stability analysis of three-dimensional boundary layer flows

    Författare :Mattias Brynjell-Rahkola; Dan Henningson; Philipp Schlatter; Ardeshir Hanifi; Spencer Sherwin; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hydrodynamic stability; transition to turbulence; global analysis; boundary layers; roughness; laminar flow control; Stokes Laplace preconditioner; optimal forcing; crossflow vortices; Ginzburg-Landau; Falkner-Skan-Cooke; Blasius; lid-driven cavity;

    Sammanfattning : This thesis considers the stability and transition of incompressible boundary layers. In particular, the Falkner–Skan–Cooke boundary layer subject to a cylindrical surface roughness, and the Blasius boundary layer with applied localized suction are investigated. LÄS MER

  7. 5. Liquid metal microscale deposition for soft and stretchable skin-like electronics : Providing a soft and gentle contact to living beings

    Författare :Bei Wang; Klas Hjort; Zhigang Wu; Magnus Berggren; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; laser patterning; sacrificial mask; liquid metal; strain sensor; skin movement; masking; shrink film; 3D conformal masking; liquid metal particles; soft electronics; stretchable electronics; compliant electronics; skin-like electronics; epidermal electronics; micro-heater; particle sintering; enteroendocrine cells; localized ectopic expression; wettability; flexography printing; conformal transfer printing; hydro printing; plant physiology; drosophila;

    Sammanfattning : Skin-like electronics could provide a soft and gentle contact with living beings for perceiving and delivering the information of pressure, strain, temperature with higher spatial resolution and sensitivity than our skin, without disturbing the user. Gallium-based liquid metal (LM) is an excellent material for soft and stretchable skin-like devices, since it has high electrical and thermal conductivity, flowability, and self-healable capability. LÄS MER