Sökning: "Boundary conditions"

Visar resultat 21 - 25 av 860 avhandlingar innehållade orden Boundary conditions.

1. 21. Edge states and transition to turbulence in boundary layers

   Författare :Taras Khapko; Dan Henningson; Philipp Schlatter; Yohann Duguet; Rich Kerswell; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer; transition to turbulence; direct numerical simulation; edge state; free-stream turbulence; bypass transition; probabilistic cellular automaton; turbulence at the onset; laminar–turbulent coexistence; laminarisation; Engineering Mechanics; Teknisk mekanik;

   Sammanfattning : The focus of this thesis is the numerical study of subcritical transition to turbulence in boundary-layer flows. For the most part, boundary layers with uniform suction are considered. Constant homogeneous suction counteracts the spatial growth of the boundary layer, rendering the flow parallel. LÄS MER

3. 22. Experimental study of the rotating-disk boundary-layer flow

   Författare :Shintaro Imayama; Henrik Alfredsson; Rebecca Lingwood; Benoît Pier; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fluid mechanics; boundary layer; rotating disk; laminar-turbulent transition; convective instability; absolute instability; secondary instability; crossflow instability; hot-wire anemometry.;

   Sammanfattning : Rotating-disk flow has been investigated not only as a simple model of cross flow instability to compare with swept-wing flow but also for industrial flow applications with rotating configurations. However the exact nature of laminar-turbulent transi- tion on the rotating-disk flow is still major problem and further research is required for it to be fully understood, in particular, the laminar-turbulent transition process with absolute instability. LÄS MER

4. 23. Nonlinear elliptic problems with boundary blow-up

   Författare :Jerk Matero; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematics; Boundary blow-up; NTA domain; fractal; p-Laplaceoperator; Mange-Ampère operator; viscosity solution; mean curvature flow; gradient estimate; Fefferman s equation; superdiffusion; entire solution; maximum principle; Primary 35J65; MATEMATIK; MATHEMATICS; MATEMATIK; matematik; Mathematics;

   Sammanfattning : A classical problem in differential geometry is the prescribed curvature problemin a bounded domain, where the task is to conformally deform the Euclidean metric to another complete Riemannian metric with a prescribed curvature function.If this function is negative, the problem is equivalent to solving a nonlinear elliptic partial differential equation with boundary blow-up. LÄS MER

5. 24. Wings, turbulent boundary layers and flow separation

   Författare :Fermin Mallor; Philipp Schlatter; Ricardo Vinuesa; Ramis Örlü; Manuel García Villalba; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Wings; turbulent boundary layers; adverse pressure gradients; flow separation; numerical simulations; wind-tunnel experiments; flow control.; Vingar; turbulenta gränsskikt; negativa tryckgradienter; avlösning; numeriska simuleringar; vindtunnel-experiment; flow control; Aerospace Engineering; Flyg- och rymdteknik; Teknisk mekanik; Engineering Mechanics;

   Sammanfattning : The present doctoral thesis investigates the turbulent flow developing around wing sections, focusing on the impact of adverse-pressure-gradient (APG) conditions on turbulent boundary layers (TBLs) and the physics of flow separation. Both experimental and numerical methods are employed to generate high-fidelity data sets and provide an in-depth analysis of the flow. LÄS MER

7. 25. Effects of boundary conditions and unsteadiness on draft tube flow

   Författare :Michel Cervantes; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Strömningslära; Fluid Mechanics;

   Sammanfattning : The present research focuses on flow properties of the elbow draft tube. This element has a major function in low head turbines, since up to half of the losses may arise there at part load. The use of computational fluid dynamic (CFD) to redisign a draft tube necessitates detailed knowledged of the boundary conditions. LÄS MER