Sökning: "Unstable flow"

Visar resultat 1 - 5 av 102 avhandlingar innehållade orden Unstable flow.

  1. 1. Unstable flow of molten polymers

    Författare :Johan Becker; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; talc; melt strength; polythylene; fillers; polypropylene; extruder; melt flow instabilities; oscillations; film blowing; composites; frequency analysis; extrudate surface; capillary extursion; polyolefine;

    Sammanfattning : .... LÄS MER

  3. 2. Stability of plane Couette flow and pipe Poiseuille flow

    Författare :Per-Olov Åsén; Gunilla Kreiss; Jonathan Goodman; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hydrodynamic stability; plane Couette flow; pipe Poiseuille flow; direct numerical simulations; resolvent; Fluid mechanics; Strömningsmekanik;

    Sammanfattning : This thesis concerns the stability of plane Couette flow and pipe Poiseuille flow in three space dimensions. The mathematical model for both flows is the incompressible Navier--Stokes equations. Both analytical and numerical techniques are used. We present new results for the resolvent corresponding to both flows. LÄS MER

  4. 3. Centrifugal compressor flow instabilities at low mass flow rate

    Författare :Elias Sundström; Mihai Mihaescu; Håkan Nilsson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Centrifugal Compressor; Large Eddy Simulation; Internal Com- bustion Engine; Aeroacoustics; Modal Flow Decomposition;

    Sammanfattning : Turbochargers play an important role in increasing the energetic efficiency andreducing emissions of modern power-train systems based on downsized recipro-cating internal combustion engines (ICE). The centrifugal compressor in tur-bochargers is limited at off-design operating conditions by the inception of flowinstabilities causing rotating stall and surge. LÄS MER

  5. 4. Nonlinear dynamics in transitional wall-bounded flows

    Författare :Miguel Beneitez Galan; Dan S. Henningson; Philipp Schlatter; Yohann Duguet; Tobias Schneider; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : This thesis focuses on numerical studies of subcritical transition to turbulence in shear flows. The thesis employs a framework based on nonlinear dynamics in the subsequent studies. The geometrical approach to subcritical transition pivots the concepts of edge manifold and edge state. LÄS MER

  7. 5. Acoustic scattering in ducts and influence of flow coupling

    Författare :Susann Boij; KTH; []
    Nyckelord :sound; vortex sheet; flow separation; end correction; Strouhal number; non-orthogonal modes; energy balance; TECHNOLOGY; TEKNIKVETENSKAP;

    Sammanfattning : The subject of this thesis is the acoustic properties offlow duct area expansions and the influence of flow-acousticcoupling at sharp edges. For low Mach number flow, significantinteraction between the sound field and the flow field canoccur at such points of flow separation. LÄS MER