Sökning: "Arnoldi method"

Visar resultat 1 - 5 av 13 avhandlingar innehållade orden Arnoldi method.

  1. 1. Krylov Subspace Methods for Linear Systems, Eigenvalues and Model Order Reduction

    Författare :Daniel Skoogh; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; eigenvalues; eigenvectors; sparse; parallel; rational; Krylov; shift; invert; Arnoldi; linear systems; iterative; model; reduction; passive; 65F15; 65F50; 65Y05; 65F10; 93A30; 93B40; rational;

    Sammanfattning : New variants of Krylov subspace methods for numerical solution of linear systems, eigenvalue, and model order reduction problems are described. A new method to solve linear systems of equations with several right-hand sides is described. LÄS MER

  3. 2. Modal Decomposition of Separated Nozzle Flow

    Författare :Ragnar Larusson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Arnoldi; axisymmetric convergent-divergent nozzle; Mode Decomposision; Flow Separation; Resonance.; Dynamic Mode Decomposision; Computational Fluid Dynamics;

    Sammanfattning : The applicability of two different eigenvalue algorithms coupled with an axisymmetric RANS solver to predict the eigenmodes of separated supersonic flow inside an axisymmetric convergent-divergent nozzle was investigated. These are the Arnoldi and the Dynamic Mode Decomposition (DMD) algorithms, respectively. LÄS MER

  4. 3. Modal Analysis of Supersonic Flow Separation in Nozzles

    Författare :Ragnar Larusson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Separated Nozzle Flow; Dynamic Mode Decomposition; Hybrid RANSLES; CFD; Modal Analysis; Arnoldi;

    Sammanfattning : Operating a convergent-divergent nozzle under overexpanded conditions can lead to supersonic flow separation in the divergent section of the nozzle. In this case, an attached oblique shock wave forms at the separation base. LÄS MER

  5. 4. Analysis and control of transitional shear flows using global modes

    Författare :Shervin Bagheri; Dan Henningson; Alessandro Bottaro; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fluid mechanics; flow control; hydrodynamic stability; global modes; jet in crossflow; flat-plate boundary layer; laminar-turbulent transition; Arnoldi method; Koopman modes; balanced truncation; direct numerical simulations.; Fluid mechanics; Strömningsmekanik;

    Sammanfattning : In this thesis direct numerical simulations are used to investigate two phenomenain shear flows: laminar-turbulent transition over a flat plate and periodicvortex shedding induced by a jet in cross flow. The emphasis is on understanding and controlling the flow dynamics using tools from dynamical systems and control theory. LÄS MER

  7. 5. Aspects of the recursive projection method applied to flow calculations

    Författare :Joakim Möller; Jesper Oppelstrup; Per Weinerfelt; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Datorteknik; applied mechanics; computer science; aerospace; Datorteknik; Computer engineering; Datorteknik;

    Sammanfattning : In this thesis, we have investigated the Recursive Projection Method, RPM, as an accelerator for computations of both steady and unsteady flows, and as a stabilizer in a bifurcation analysis.The criterion of basis extraction is discussed. LÄS MER