Sökning: "high order finite difference"

Visar resultat 16 - 20 av 77 avhandlingar innehållade orden high order finite difference.

1. 16. Higher order finite difference methods for wave propagation problems

   Författare :Eva Mossberg; Bertil Gustafsson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Numerical Analysis; Numerisk analys;

   Sammanfattning : Wave propagation is described by the wave equation, or in the time-periodic case, by the Helmholtz equation. For problems with small wavelengths, high order discretizations must be used to resolve the solution. Two different techniques for finding compact finite difference schemes of high order are studied and compared. LÄS MER

3. 17. Weak Boundary and Interface Procedures for Wave and Flow Problems

   Författare :Qaisar Abbas; Jan Nordström; Peter Eliasson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; weak boundary conditions; multiple penalty; finite difference methods; summation-by-parts; high order scheme; hybrid methods; MUSCL scheme; shocks; stability; energy estimate; steady-state; non-reflecting; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

   Sammanfattning : In this thesis, we have analyzed the accuracy and stability aspects of weak boundary and interface conditions (WBCs) for high order finite difference methods on Summations-By-Parts (SBP) form. The numerical technique has been applied to wave propagation and flow problems. LÄS MER

4. 18. Efficient Simulation of Wave Phenomena

   Författare :Martin Almquist; Ken Mattsson; Gianluca Iaccarino; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; finite difference method; high-order accuracy; stability; summation by parts; simultaneous approximation term; quantum mechanics; Dirac equation; local time-stepping; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

   Sammanfattning : Wave phenomena appear in many fields of science such as acoustics, geophysics, and quantum mechanics. They can often be described by partial differential equations (PDEs). As PDEs typically are too difficult to solve by hand, the only option is to compute approximate solutions by implementing numerical methods on computers. LÄS MER

5. 19. Stable High Order Finite Difference Methods for Wave Propagation and Flow Problems on Deforming Domains

   Författare :Samira Nikkar; Jan Nordström; Gunilla Kreiss; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : We construct stable, accurate and efficient numerical schemes for wave propagation and flow problems posed on spatial geometries that are moving, deforming, erroneously described or non-simply connected. The schemes are on Summation-by-Parts (SBP) form, combined with the Simultaneous Approximation Term (SAT) technique for imposing initial and boundary conditions. LÄS MER

7. 20. Hybrid Methods for Unsteady Fluid Flow Problems in Complex Geometries

   Författare :Jing Gong; Jan Nordström; Gunilla Efraimsson; Mark H. Carpenter; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; hybrid methods; finite difference methods; finite volume methods; coupling procedure; stability; efficiency; artificial dissipation; Numerical analysis; Numerisk analys; Scientific Computing; Beräkningsvetenskap; Beräkningsvetenskap med inriktning mot numerisk analys;

   Sammanfattning : In this thesis, stable and efficient hybrid methods which combine high order finite difference methods and unstructured finite volume methods for time-dependent initial boundary value problems have been developed. The hybrid methods make it possible to combine the efficiency of the finite difference method and the flexibility of the finite volume method. LÄS MER