Sökning: "pseudo turbulence"

Visar resultat 1 - 5 av 7 avhandlingar innehållade orden pseudo turbulence.

1. 1. Flow and turbulence in the discharge stream of different agitators for stirred tanks

   Författare :Tamás Kovács; Livsmedelsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; fluiddynamik; Gaser; plasmas; fluid dynamics; Gases; Livsmedelsteknik; Food and drink technology; Scaba; 6SRGT; pseudo turbulence; Rushton; stirred tank; plasma; Mechanical engineering; hydraulics; vacuum technology; vibration and acoustic engineering; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik;

   Sammanfattning : In this thesis, the fluid dynamic properties of the conventional Rushton turbine and another impeller type, the Scaba Radial flow Gas dispersing Turbine (with six concave blades) are compared. For comparison, point-wise velocity measurements were made in the discharge of the two turbine types using Hot-Wire Anemometry in constant temperature mode (CTA) with a split film probe. LÄS MER

3. 2. Modelling and simulation of turbulence subject to system rotation

   Författare :Olof Grundestam; Arne Johansson; Sharath Girimaji; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Direct numerical simulations; least-squares method; turbulence model; nonlinear modelling; system rotation; streamline curvature; high-lift aerodynamics; Fluid mechanics; Strömningsmekanik;

   Sammanfattning : Simulation and modelling of turbulent flows under influence of streamline curvature and system rotation have been considered. Direct numerical simulations have been performed for fully developed rotating turbulent channel flow using a pseudo-spectral code. The rotation numbers considered are larger than unity. LÄS MER

4. 3. Explicit algebraic subgrid-scale stress and passive scalar flux modeling in large eddy simulation

   Författare :Amin Rasam; Arne V. Johansson; Shia-Hui Peng; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; Large eddy simulation; explicit algebraic subgrid-scale model; passive scalar; stochastic modeling; backscatter; Fluid mechanics; Strömningsmekanik;

   Sammanfattning : The present thesis deals with a number of challenges in the field of large eddy simulation (LES). These include the performance of subgrid-scale (SGS) models at fairly high Reynolds numbers and coarse resolutions, passive scalar and stochastic modeling in LES. LÄS MER

5. 4. Anisotropy-resolving subgrid-scale modelling using explicit algebraic closures for large eddy simulation

   Författare :Amin Rasam; Arne Johansson; Bernard Geurts; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; large eddy simulation; explicit algebraic subgridscale model; passive scalar; stochastic modelling; periodic hill flow; Engineering Mechanics; Teknisk mekanik;

   Sammanfattning : The present thesis deals with the development and performance analysis ofanisotropy-resolving models for the small, unresolved scales (”sub-grid scales”,SGS) in large eddy simulation (LES). The models are characterised by a descriptionof anisotropy by use of explicit algebraic models for both the subgridscale(SGS) stress tensor (EASSM) and SGS scalar flux vector (EASSFM). LÄS MER

7. 5. Numerical and modelling aspects of large-eddy and hybrid simulations of turbulent flows

   Författare :Matteo Montecchia; Arne V. Johansson; Gert Brethouwer; Stefan Wallin; Dominic Von Terzi; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; turbulence; wall-bounded flows; large-eddy simulation; SGS modelling; OpenFOAM; hybrid RANS-LES; Engineering Mechanics; Teknisk mekanik;

   Sammanfattning : In this study, the explicit algebraic sub-grid scale (SGS) model (EAM) has been extensively validated in wall-resolved large-eddy simulations (LES) of wall-bounded turbulent flows at different Reynolds numbers and a wide range of resolutions. Compared to eddy-viscosity based models, the formulation of the EAM is more consistent with the physics and allows to accurately capture SGS anisotropy,which is relevant especially close to walls. LÄS MER