Sökning: "periodic boundary condition"

Visar resultat 1 - 5 av 23 avhandlingar innehållade orden periodic boundary condition.

1. 1. 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

3. 2. Moisture Transport in Porous Media. Modelling Based on Kirchhoff Potentials

   Författare :Jesper Arfvidsson; Avdelningen för Byggnadsfysik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; moisture distribtion; wood drying; wood; diffusion coefficient; numerical modelling; moisture flow; Moisture; transient measurements; periodic boundary condition; penetration depth; sorption coefficient; non-linear moisture flow; calculation model; anisitropy; Kirchhoff potentials; evaluation; moisture transport; Building construction; Byggnadsteknik;

   Sammanfattning : The work presented in this thesis is focused on the development of the new concept to describe isothermal moisture transport using Kirchhoff potentials. The first four papers deal with moisture transport in porous media using Kirchhoff potentials. The last three papers deal with wood. LÄS MER

4. 3. Metoder att välja korrektioner vid fuktberäkningar med variabelt utomhusklimat

   Författare :Eva Harderup; Avdelningen för Byggnadsfysik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; moisture flow; Moisture; numerical modelling; calculation model; moisture distribution; non-linear moisture flow; external climate; moisture calculations; corrections; Building construction; periodic boundary condition; reference year; Byggnadsteknik;

   Sammanfattning : Determination of the design conditions for moisture resistance requires in a Moisture Design number of different moisture calculations to be made in order to determine the moisture status within, or on the surface of, a structure. The objective of this work has been to ascertain how to allow for variations in climate data in order to be able to determine the most unfavourable moisture status likely to be encountered during the life of a building. LÄS MER

5. 4. Scattering and propagation of electromagnetic waves in planar and curved periodic structures - applications to plane wave filters, plane wave absorbers and impedance surfaces

   Författare :Ola Forslund; KTH; []
   Nyckelord :electromagnetic scattering; periodic structure; frequency selectiove structure; frequency selective surface;

   Sammanfattning : The subject of this thesis is scattering of electromagneticwaves from planar and curved periodic structures. The problemspresented are solved in the frequency domain.Scattering from planar structures with two-dimensionalperiodic dependence of constitutive parameters is treated. LÄS MER

7. 5. Scaling effects and homogenization of reaction-diffusion problems with nonlinear drift

   Författare :Vishnu Raveendran; Adrian Muntean; Irina Pettersson; Karlstads universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; homogenization; asymptotic expansion with drift; two-scale convergence with drift; effective transmission condition; dimension reduction; two-scale system; nonlinear dispersion; Matematik; Mathematics;

   Sammanfattning : We study the periodic homogenization of reaction-diffusion problems with nonlinear drift describing the transport of interacting particles in composite materials. The microscopic model is derived as the hydrodynamic limit of a totally asymmetric simple exclusion process for a population of interacting particles crossing a domain with obstacles. LÄS MER