Sökning: "boundary integral"

Visar resultat 1 - 5 av 88 avhandlingar innehållade orden boundary integral.

1. 1. Boundary integral methods for Stokes flow : Quadrature techniques and fast Ewald methods

   Författare :Oana Marin; Anna-Karin Tornberg; Anita Layton; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; boundary integral; Stokes flow; quadrature rule; Ewald decomposition;

   Sammanfattning : Fluid phenomena dominated by viscous effects can, in many cases, be modeled by the Stokes equations. The boundary integral form of the Stokes equations reduces the number of degrees of freedom in a numerical discretization by reformulating the three-dimensional problem to two-dimensional integral equations to be discretized over the boundaries of the domain. LÄS MER

3. 2. On the modelling of ultrasonic testing using boundary integral equation methods

   Författare :Jonathan Westlund; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Boundary element method; Regularization; Ultrasonics; Boundary integral equation method; T matrix.; Elastic waves; Nondestructive testing; Scattering;

   Sammanfattning : Ultrasonic nondestructive testing has important applications in, for example, the nuclearpower and aerospace industries, where it is used to inspect safety-critical parts for flaws.For safe and reliable testing, mathematical models of the ultrasonic measurement systemsare invaluable tools. LÄS MER

4. 3. Numerical approximations of time domain boundary integral equation for wave propagation

   Författare :Andreas Atle; KTH; []
   Nyckelord :MOT; Marching on in time; boundary integral equations;

   Sammanfattning : Boundary integral equation techniques are useful in thenumerical simulation of scattering problems for wave equations.Their advantage over methods based on partial di.erentialequations comes from the lack of phase errors in the wavepropagation and from the fact that only the boundary of thescattering object needs to be discretized. LÄS MER

5. 4. Approximations of Integral Equations for WaveScattering

   Författare :Andreas Atle; Björn Engquist; Richard Tsai; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Integral equations; Marching on in time; On surface radiation condition; Physical Optics; Numerical analysis; Numerisk analys;

   Sammanfattning : Wave scattering is the phenomenon in which a wave field interacts with physical objects. An incoming wave is scattered at the surface of the object and a scattered wave is produced. Common practical cases are acoustic, electromagnetic and elastic wave scattering. 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