Search for dissertations about: "delay gradients"

Showing result 6 - 10 of 18 swedish dissertations containing the words delay gradients.

  2. 6. Boundary layer streaks as a novel laminar flow control method

    Author : Sohrab Sattarzadeh Shirvan; Jens H. M. Fransson; Edward B. White; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer stability; laminar to turbulent transition; laminar flow control; drag reduction; Tollmien-Schlichting waves; oblique waves; streaky boundary layers; miniature vortex generators; discrete suction;

    Abstract : A novel laminar flow control based on generation of spanwise mean velocity gradients (SVG) in a flat plate boundary layer is investigated where disturbances of different types are introduced in the wall-bounded shear layer. The experimental investigations are aimed at; (i) generating stable and steady streamwise streaks in the boundary layer which set up spanwise gradients in the mean flow, and (ii) attenuating disturbance energy growth in the streaky boundary layers and hence delaying the onset of turbulence transition. READ MORE

  4. 7. Adjoint-based aerodynamic shape optimization

    Author : Olivier Amoignon; Martin Berggren; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Numerical Analysis; Numerisk analys;

    Abstract : An adjoint system of the Euler equations of gas dynamics is derived in order to solve aerodynamic shape optimization problems with gradient-based methods. The derivation is based on the fully discrete flow model and involves differentiation and transposition of the system of equations obtained by an unstructured and node-centered finite-volume discretization. READ MORE

  5. 8. Stability and transition of three-dimensional boundary layers

    Author : Seyed Mohammad Hosseini; Ardeshir Hanifi; Vassilios Theofilis; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Receptivity; stability; optimal growth; three-dimensional boundary layers; crossflow instability; roughness control; freestream turbulence; secondary instability;

    Abstract : A focus has been put on the stability characteristics of different flow types existing on air vehicles. Flow passing over wings and different junctions on an aircraft face numerous local features, ranging from different pressure gradients, to interacting boundary layers. READ MORE

  6. 9. Asynchronous First-Order Algorithms for Large-Scale Optimization : Analysis and Implementation

    Author : Arda Aytekin; Mikael Johansson; Lin Xiao; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; convex; optimization; asynchronous; algorithms; parallel; distributed; large-scale; big data; software; serverless; Electrical Engineering; Elektro- och systemteknik;

    Abstract : Developments in communication and data storage technologies have made large-scale data collection more accessible than ever. The transformation of this data into insight or decisions typically involves solving numerical optimization problems. READ MORE

  7. 10. Atrioventricular synchronous pacing in hypertrophic obstructive cardiomyopathy

    Author : Fredrik Gadler; Karolinska Institutet; Karolinska Institutet; []
    Keywords : HOCM; pacing; LVOTobstruction; quality of life;

    Abstract : The study addresses major issues of cardiac pacing in hypertrophic obstructive cardiomyopathy (HOCM). The influence of ventricular pacing site and atrioventricular (AV)-delay on left ventricular outflow tract (LVOT) gradient. READ MORE