Sökning: "finite difference time domain"

Visar resultat 1 - 5 av 80 avhandlingar innehållade orden finite difference time domain.

  1. 1. Efficient time-domain modelling suitable for optimising thermoacoustic devices

    Författare :Stig Kleiven; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; finite-difference; thermoacoustics; time domain; optimisation; equivalent source method; active control;

    Sammanfattning : Thermoacoustic heat pumps use acoustic work to transfer heat from cold to hot temperatures. Such devices benefit from being environmentally friendly, robust and simple. However, in practice these devices have too low efficiency and power compared to their conventional counterparts. LÄS MER

  3. 2. Hybrid Solvers for the Maxwell Equations in Time-Domain

    Författare :Fredrik Edelvik; Per Lötstedt; Jan Hesthaven; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Maxwell s equations; time-domain; finite volume methods; finite element methods; hybrid solver; dispersive materials; thin wires; Beräkningsvetenskap; Scientific Computing;

    Sammanfattning : The most commonly used method for the time-domain Maxwell equations is the Finite-Difference Time-Domain method (FDTD). This is an explicit, second-order accurate method, which is used on a staggered Cartesian grid. The main drawback with the FDTD method is its inability to accurately model curved objects and small geometrical features. LÄS MER

  4. 3. A hybrid finite element method for electromagnetics with applications in time-domain

    Författare :DAVID DEGERFELDT; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Nitsche s method; antenna arrays; NASA almond; edge elements; scattering; explicit-implicit time-stepping; Maxwell s equations; Finite Element Method; mass lumping; stability analysis; Finite-Differences Time-Domain; periodic structures; shape and material optimization;

    Sammanfattning : In this thesis, a new hybrid method that combines the Finite Element Method (FEM) with the Finite-Difference in Time-Domain (FDTD) method is presented. Tetrahedrons in the unstructured FEM region are connected directly to thehexahedrons in the structured FDTD region. LÄS MER

  5. 4. Thermoacoustic refrigerators: Time-domain modelling and experimental setup

    Författare :Stig Kleiven; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; finite-difference time-domain; refrigerator; thermoacoustics; equivalent source method;

    Sammanfattning : Thermoacoustic refrigerators use acoustic waves to transfer heat. Although their benefits compared with their vapour-compression counterparts are environmental friendliness, robustness and simplicity, they are currently still less efficient than traditional vapour-compression refrigerators. LÄS MER

  7. 5. Direct and Inverse Methods for Waveguides and Scattering Problems in the Time Domain

    Författare :Erik Abenius; Per Lötstedt; Mats Gustafsson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Maxwell s equations; time-domain; FDTD; finite-element; hybrid; thin sheet; waveguide; PML; inverse scattering; adjoint; gradient-based; minimization; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Sammanfattning : Numerical simulation is an important tool in understanding the electromagnetic field and how it interacts with the environment. Different topics for time-domain finite-difference (FDTD) and finite-element (FETD) methods for Maxwell's equations are treated in this thesis. LÄS MER