Sökning: "boundary method"

Visar resultat 1 - 5 av 762 avhandlingar innehållade orden boundary method.

1. 1. The material distribution method : analysis and acoustics applications

   Författare :Fotios Kasolis; Martin Berggren; Volker Schulz; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Material distribution method; fictitious domain method; finite element method; Helmholtz equation; linear elasticity; shape optimization; topology optimization;

   Sammanfattning : For the purpose of numerically simulating continuum mechanical structures, different types of material may be represented by the extreme values {,1}, where 0.... LÄS MER

3. 2. Potential Flow Panel Methods for the Calculation of Free-surface Flows with Lift

   Författare :Carl-Erik Janson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; desingularized; shape optimization; Rankine source; waves; OCTOPUS; dipole; MMA; Dawson operator; boundary layer; vortex; Method of Moving Asymptotes; nonlinear; sailing yacht; four point operator; surface piercing wing; Navier-Stokes; numerical method; lift force; raised panel method; discrete Fourier transform; collocation point shift; potential flow; CFD; free surface; induced drag; SHIPFLOW; dispersion; damping; analytical method; hydrofoil;

   Sammanfattning : Two non-linear Rankine-source panel methods are developed and implemented in the same computer code. The first method uses a four-point upwind operator on the free-surface to compute the velocity derivatives and to enforce the radiation condition while the second method uses an analytical expression for the velocity derivatives and a collocation point shift one panel upstream to prevent upstream waves. LÄS MER

4. 3. Numerical Conformal Mappings for Waveguides

   Författare :Anders Andersson; Börje Nilsson; Joachim Toft; Michael Benedicks; Växjö universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; waveguide; building block method; numerical conformal mappings; Schwarz–Christoffel mapping; rounded corners method; approximate curve factors; outer polygon method; boundary curvature; zipper method; geodesic algorithm; acoustic wave scattering; electro-magnetic wave scattering; Applied mathematics; Tillämpad matematik; Mathematics; Matematik;

   Sammanfattning : Acoustic or electro-magnetic scattering in a waveguide with varying direction and cross-section can be re-formulated as a two-dimensional scattering problem, provided that the variations take place in only one dimension at a time. By using the so-called Building Block Method, it is possible to construct the scattering properties of a combination of scatterers when the properties of each scatterer are known. LÄS MER

5. 4. Optimisation and control of boundary layer flows

   Författare :Antonios Monokrousos; Dan S. Henningson; Per Lötstedt; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer; control; estimation; optimal disturbances; Lagrange method; Engineering mechanics; Teknisk mekanik;

   Sammanfattning : Both optimal disturbances and optimal control are studied by means of numerical simulations for the case of the flat-plate boundary-layer flow. The optimisation method is the Lagrange multiplier technique where the objective function is the kinetic energy of the flow perturbations and the constraints involve the linearised Navier–Stokes equations. LÄS MER

7. 5. Boundary layer streaks as a novel laminar flow control method

   Författare :Sohrab Sattarzadeh Shirvan; Jens H. M. Fransson; Edward B. White; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer stability; laminar to turbulent transition; laminar flow control; drag reduction; Tollmien-Schlichting waves; oblique waves; streaky boundary layers; miniature vortex generators; discrete suction;

   Sammanfattning : A novel laminar flow control based on generation of spanwise mean velocity gradients (SVG) in a flat plate boundary layer is investigated where disturbances of different types are introduced in the wall-bounded shear layer. The experimental investigations are aimed at; (i) generating stable and steady streamwise streaks in the boundary layer which set up spanwise gradients in the mean flow, and (ii) attenuating disturbance energy growth in the streaky boundary layers and hence delaying the onset of turbulence transition. LÄS MER