Sökning: "high order finite difference"

Visar resultat 21 - 25 av 77 avhandlingar innehållade orden high order finite difference.

1. 21. 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. 22. Uncertainty Quantification and Numerical Methods for Conservation Laws

   Författare :Per Pettersson; Jan Nordström; Gianluca Iaccarino; Gunilla Kreiss; Rémi Abgrall; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; uncertainty quantification; polynomial chaos; stochastic Galerkin methods; conservation laws; hyperbolic problems; finite difference methods; finite volume methods; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

   Sammanfattning : Conservation laws with uncertain initial and boundary conditions are approximated using a generalized polynomial chaos expansion approach where the solution is represented as a generalized Fourier series of stochastic basis functions, e.g. orthogonal polynomials or wavelets. LÄS MER

4. 23. Thermal stresses in load-bearing glass-timber components

   Författare :Karin Lundstedt; Erik Serrano; Ola Dahlblom; Linnéuniversitetet; []
   Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; Thermal stresses; thermal failure; glass and wood construction; incident solar radiation; shading; cracks; temperature difference; finite element method.; Technology byts ev till Engineering ; Teknik;

   Sammanfattning : Thermal stresses can arise in glass used in architectonic realisations in buildings as a result of solar irradiation:  that is, sunlight.  The magnitude of these thermal stresses depends on the temperature conditions in the glass in terms of the temperature differences between warm and cold areas. LÄS MER

5. 24. Analysis of boundary and interface closures for finite difference methods for the wave equation

   Författare :Siyang Wang; Gunilla Kreiss; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Scientific Computing; Beräkningsvetenskap;

   Sammanfattning : We consider high order finite difference methods for the wave equations in the second order form, where the finite difference operators satisfy the summation-by-parts principle. Boundary conditions and interface conditions are imposed weakly by the simultaneous-approximation-term method, and non-conforming grid interfaces are handled by an interface operator that is based on either interpolating directly between the grids or on projecting to piecewise continuous polynomials on an intermediate grid. LÄS MER

7. 25. A high-order accurate, collocated boundary element method for wave propagation in layered media

   Författare :Elena Sundkvist; Kurt Otto; Elisabeth Larsson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Numerical Analysis; Numerisk analys;

   Sammanfattning : The ultimate goal of this research is to construct a hybrid model for sound propagation in layered underwater environments with curved boundaries by employing a differential formulation for inhomogeneous layers and a boundary integral formulation for homogeneous layers. The discretization of the new hybrid model is a combination of a finite difference method for the Helmholtz equation for inhomogeneous media and a collocated boundary element method (BEM) for the integral equation for homogeneous media, while taking special care of the open boundaries and the common interface. LÄS MER