Sökning: "Linear harmonic"

Visar resultat 1 - 5 av 95 avhandlingar innehållade orden Linear harmonic.

  1. 1. Linear and non-linear dynamics of non-autonomous flows

    Författare :J. Simon Kern; Dan S. Henningson; Ardeshir Hanifi; Peter J. Schmid; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Time-dependent flows; linear stability; non-linear dynamics; Floquet analysis; optimally time-dependent modes; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : Fluid flows subject to time-dependent external forces or boundary conditions are ubiquitous in biology and technical applications. Whether one considers birds flying by flapping their wings or the gust response of wind turbines, the flow is non-autonomous. LÄS MER

  3. 2. Modeling of Unsteady Flow Effects in Throughflow Calculations

    Författare :Magnus Stridh; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; rotor-stator interaction; mixing-plane; linear Navier-Stokes; cascade; turbomachinery; transport equation; Linear harmonic; compressor; throughflow; turbine; Deterministic stress terms;

    Sammanfattning : In this work an evaluation of a deterministic stress transport model and a linearized Navier-Stokes harmonic approach for including unsteady effects in the steady mixing-plane computations of a multistage transonic compressor has been performed. The results of these two models are compared with those of time-average time-accurate solutions. LÄS MER

  4. 3. Modeling Unsteady flow Effects in 3D Throughflow Calculations

    Författare :Magnus Stridh; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; throughflow; turbomachinery; mixing-plane; rotor-stator interaction; cascade; Deterministic stress terms; Linear harmonic; compressor; preconditioned GMRES; Unsteady; linear Navier-Stokes; turbine;

    Sammanfattning : The flow field in a transonic multistage compressor is compressible, three-dimensional and highly unsteady and can be predicted in principle by the exact time-accurate Navier-Stokes equations. The high Reynolds number encountered in multistage turbomachinery together with the wall-bounded nature of the flow environment however prevent the use of DNS to solve the exact N-S equations. LÄS MER

  5. 4. Theoretical perspectives on ultrafast and non-linear spectroscopy

    Författare :Emil Vinas Boström; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Non-linear optics; Ultrafast dynamics; Non-equilibrium Green s functions; Density functional theory; Multi-photon absorption; Second harmonic generation; Desorption dynamics; Auger decay; Charge-separation dynamics; Quantum Zeno effect; Fysicumarkivet A:2018:Vinas Boström;

    Sammanfattning : In this thesis we discuss a theoretical description of ultrafast and non-linear spectroscopy. Due to the high intensities and ultrashort pulse durations involved in such experiments, it is necessary to use an explicitly time-dependent formalism. LÄS MER

  7. 5. Non-linear attosecond physics at 100 eV

    Författare :Alexander Muschet; Laszlo Veisz; Piotr Matyba; Per Eng-Johnsson; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; extreme ultraviolet XUV ; non-linear XUV – matter interaction; high-harmonic generation; photoionization; attosecond physics; isolated attosecond pulses; attosecond XUV pump – XUV probe spectroscopy; fysik; Physics;

    Sammanfattning : Non-linear interactions between light and matter have nowadays a broad range of applications. They are used for frequency doubling in simple laser pointers as well as for a variety of purposes in complex laser systems like the one presented in this thesis. LÄS MER