Sökning: "Complex Turbulent Flows"

Visar resultat 11 - 15 av 66 avhandlingar innehållade orden Complex Turbulent Flows.

1. 11. 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

3. 12. Computational modeling of complex flow : Doctoral thesis at Chalmers University of Technology

   Författare :Johan Hoffman; Claes Johnson; Ragnar Winter; Chalmers; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : In this thesis we consider the following aspects of computational modeling of complex flows: (i) subgrid modeling, (ii) stability, (iii) a posteriori error estimation, and (iv) computational platform. We develop a framework for adaptivity and error control for multiscale problems, in particular for turbulent flow, based on a posteriori error estimates. LÄS MER

4. 13. Towards Improved Scale-Resolving Modeling and Simulations of Turbulent Flows

   Författare :Magnus Carlsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hybrid RANS-LES; Numerical methods; Synthetic Turbulence; Compressible flow; Scale-resolving simu- lation; High-order gradient reconstruction; Turbulence modelling;

   Sammanfattning : Scale-resolving simulations are viewed as powerful means for predicting complex turbulentflows, as often encountered in aeronautical applications. However, since turbulent scalesspan over a considerable range from the smallest Kolmogorov scales to the largest ofequivalence to configuration size, scale-resolving computations are often demandingon computational resources and, furthermore, on the underlying numerical methodsused in the simulations. LÄS MER

5. 14. Numerical modeling of deforming bubble transport related to cavitating hydraulic turbines

   Författare :Daniel Lörstad; Institutionen för energivetenskaper; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Gases; fluid dynamics; plasmas; Gaser; fluiddynamik; plasma; Energy research; Energiforskning; Direction Averaged Curvature DAC ; Direction Averaged Normal DAN ; Volume of Solid VOS ; Volume of Fluid VOF ; Lagrangian Particle Tracking LPT ; Large Eddy Simulation LES ; bubble; multiphase; turbulent flows; CFD; hydro-turbine;

   Sammanfattning : Cavitation is a problem in many hydroelectric power plants since it can cause adverse effects on performance and damage to nearby solid surfaces. The concerns of this thesis are the numerical aspects of flow simulations in cavitating hydraulic turbines which contain several difficulties: turbulent and complex flows, steady and moving parts of the geometry, bubble transport and cavitation development. LÄS MER

7. 15. Numerical and Experimental study of shock boundary layer interaction in unsteady transonic flow

   Författare :Olivier Bron; KTH; []
   Nyckelord :Shock Boundary Layer Interaction; Shock Motion; Unsteady Flows; Nozzle Flows; Potential Interaction; Back Pressure Perturbations;

   Sammanfattning : A prerequisite for aeroelastic stability prediction inturbomachines is the understanding of the fluctuatingaerodynamic forces acting on the blades. Unsteady transonicflows are complex because of mutual interactions betweentravelling pressure waves, outlet disturbances, shock motion,and fluctuating turbulent boundary layers. LÄS MER