Sökning: "dan s"

Visar resultat 1 - 5 av 296 avhandlingar innehållade orden dan s.

1. 1. Adaptive and model-based control in laminar boundary-layer flows

   Författare :Nicolò Fabbiane; Dan S. Henningson; Aimee S. Morgans; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Flow control; Control theory; Optimal control; Adaptive control; Boundary-layer flow; Fluid dynamics; Plasma actuator; Surface hot-wire; Transition delay;

   Sammanfattning : In boundary-layer flows it is possible to reduce the friction drag by breaking the path from laminar to turbulent state. In low turbulence environments, the laminar-to-turbulent transition is dominated by local flow instabilities – Tollmien-Schlichting (TS) waves – that exponentially grows while being con- vected by the flow and, eventually, lead to transition. LÄS MER

3. 2. Modelling and control of turbulent and transitional flows

   Författare :Pierluigi Morra; Dan S. Henningson; Ardeshir Hanifi; André V. G. Cavalieri; Shervin Bagheri; Aimee S. Morgans; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; reduced order modeling; flow control; resolvent analysis; transi- tional boundary layer; turbulent boundary layer; drag reduction; high-fidelity wall-turbulence modelling; modellreduktion; strömningskontroll; resolvent analys; laminär- turbulent omslag; turbulent gränsskikt; motståndsminskning; väggturbulens modellering; Engineering Mechanics; Teknisk mekanik;

   Sammanfattning : The dynamics of fluid motion can accurately be described by the Navier– Stokes equations. Manipulating these equations to reduce their complexity but preserving their main characteristics has always been a key research activity in the field of fluid mechanics. LÄS MER

4. 3. Ghana in search of development : The challenge of governance, economic management and institution building

   Författare :Dan-Bright S. Dzorgbo; Uppsala universitet; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Sociology; Ghana; State; Development; Governance; Economic Management; Institutions; Praetorianism; Neopatrimonialism; Socioeconomic and Political Environment; Sociologi; Sociology; Sociologi; Sociology; sociologi;

   Sammanfattning : Why did Ghana, a country that was favourably endowed in its economic and social life, and judged to have considerable head start over other countries in Sub-Saharan Africa in the 1950s, and for which all predictions pointed to a bright future, come to experience a classic socioeconomic decline and is now struggling to survive?This study endeavours to explain how and why this happened. Combining sociological, economic and political, as well as institutional perspectives at the methodological level, the study focuses on the interplay between state politics and socioeconomic development. LÄS MER

5. 4. Numerical computations of wind turbine wakes

   Författare :Stefan S. A. Ivanell; Dan Henningsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Applied mechanics; Wind Energy; Wind Turbine; Wake; Circulation; Vortex; CFD; EllipSys3D; Actuator line; Teknisk mekanik; Engineering mechanics; Teknisk mekanik;

   Sammanfattning : Numerical simulations using CFD methods are performed for wind turbine applications. The aim of the project is to get a better understanding of the wake behaviour, which is needed since today’s industrial design codes for wind power applications are based on the BEM (Blade Element Momentum) method. LÄS MER

7. 5. Numerical computations of wind turbine wakes

   Författare :Stefan S. A. Ivanell; Dan Henningson; Peinke Joachim; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Actuator Line Model; Actuator Disc Model; Wind Turbine Wake; CFD; LES; EllipSys3D; Fluid mechanics; Strömningsmekanik;

   Sammanfattning : Numerical simulations of the Navier-Stokes equations are performed to achieve a better understanding of the behaviour of wakes generated by wind turbines. The simulations are performed by combining the in-house developed computer code EllipSys3D with the actuator line and disc methodologies. LÄS MER