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Showing result 1 - 5 of 20 swedish dissertations matching the above criteria.

  2. 1. Theoretical and Experimental Investigations of Nonlinear Flame Instability

    Author : Li-Zheng Ma; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; nonlinear hydrodynamic instability; flame propagation and stretch effects; shock induced flame instability; tulip flame formation; interface tracking; the Schlieren technique; level set approach;

    Abstract : Flame instability is both important and difficult to understand. Mechanisms of instability are complex, because instability often involves an interaction between several different physical phenomena, such as an unsteady chemical reaction, unsteady flame propagation generating an unsteady flow, acoustic waves or shock waves. READ MORE

  4. 2. Inflation and Instabilities of Hyperelastic Membranes

    Author : Amit Patil; Anders Eriksson; Arne Nordmark; Peter Hansbo; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Membranes; Constrained inflation; Energy release rate; Adhesive contact condition; Limit point; Bifurcation point; Wrinkling; Tension field theory; Pressure induced instability.; Teknisk mekanik; Engineering Mechanics;

    Abstract : The applications of membranes are increasing rapidly in various fields of engineering and science. The geometric, material, force and contact non-linearities complicate their analysis, which increases the demand for computationally efficient methods and interpretation of counter-intuitive behaviours. READ MORE

  5. 3. Effects of free-stream turbulence and three-dimensional roughness on boundary layer transition

    Author : Santhosh Babu Mamidala; Jens H. M. Fransson; Bengt E. G. Fallenius; Jonathan Morrison; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary-layer transition; intermittency; free-stream turbulence; electret microphones; isolated roughness; sinuous instability; varicose instability; Engineering Mechanics; Teknisk mekanik;

    Abstract : External disturbances such as free-stream turbulence (FST), and isolated three-dimensional roughness are strong disturbance sources to the laminar boundary layers (BLs), which can lead to a rapid transition to turbulence. The transition process eventuates to increase in skin-friction coefficient and heat transfer rate and hence, both of the aforementioned disturbance sources have practical importance. READ MORE

  6. 4. Numerical instability investigations for thin membranes

    Author : Yang Zhou; Anders Eriksson; Arne Nordmark; Reijo Kouhia; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Abstract : Membrane structures are commonly used in many fields. The studies of these structures are of increasing interest. The projects in this thesis focus on the evaluations of equilibrium states for pressurized membranes under different problem settings, using finite element methods, and the corresponding instability behaviors. READ MORE

  7. 5. Drift and Mirror Modes in Magnetized Plasmas

    Author : Ingmar Sandberg; Padma Shukla; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Astronomy; tokamak plasma; drift waves; space plasma; mirror instability.; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Space and Plasma Physics; rymd- och plasmafysik;

    Abstract : Low frequency plasma instabilities driven by plasma inhomogeneity and velocity anisotropies are major candidates for the explanation of various phenomena observed in fusion and space plasmas. For low-β fusion plasma, the influence of plasma rotation and finite ion temperature on the structure and the type of toroidal drift eigenmodes in tokamaks is investigated rigorously, including the effects induced by the toroidal geometry such as the coupling mode, the radial variation of plasma rotation velocity and the magnetic shear. READ MORE