Validation of depth-averaged mixing length turbulence model for uniform channel flows/

Download
2014
Karaman, Çağrı Hasan
A one-dimensional depth averaged turbulence model based on volumetric mixing length definition is developed for shallow flows. Numerical solution of the model is done using finite volume method for steady, uniform closed duct flows to observe lateral momentum exchange over depth discontinuities. The model is verified by comparison to two-dimensional numerical solutions and to the experimental data available in the literature. The model is then applied to uniform free surface flows in rectangular and compound channels. Comparisons with two-dimensional numerical solutions as well as experimental data taken from the literature indicated that depth integrated velocity and bed shear stresses are successfully predicted by the model with good accuracy.

Suggestions

Incompressible flow simulations using least squares spectral element method on adaptively refined triangular grids
Akdağ, Osman; Sert, Cüneyt; Department of Mechanical Engineering (2012)
The main purpose of this study is to develop a flow solver that employs triangular grids to solve two-dimensional, viscous, laminar, steady, incompressible flows. The flow solver is based on Least Squares Spectral Element Method (LSSEM). It has p-type adaptive mesh refinement/coarsening capability and supports p-type nonconforming element interfaces. To validate the developed flow solver several benchmark problems are studied and successful results are obtained. The performances of two different triangular ...
Improving flow structure and natural convection within fin spacings of plate fin heat sinks
Özet, Mehmet Erdem; Tarı, İlker; Department of Mechanical Engineering (2015)
The main objectives of this thesis are to numerically investigate the previously observed recirculation zones and longitudinal vortices that occur in low fin height plate finned horizontal heat sinks and to improve the flow structures and heat transfer in these zones using various approaches with the help of simulations performed using commercially available CFD software. The approaches used for improvements are replacing the outer most fins with higher ones, introducing gaps on the length of the fins in va...
Development of a discrete adjoint-based aerodynamic shape optimization tool for natural laminar flows
Kaya, Halil; Tuncer, İsmail Hakkı; Department of Aerospace Engineering (2020)
An adjoint-based aerodynamic shape optimization framework for natural laminar flows is developed. A Reynolds-Averaged Navier-Stokes flow solver with the Spalart-Allmaras turbulence model is coupled with the recently developed Bas-Cakmakcioglu transition model in order to predict laminar to turbulent transition onset. In the gradient-based optimization process, the sensitivity derivatives required by the optimization algorithm is obtained by the discrete adjoint method, which is developed for the in-house fl...
Design and analysis of a vertical axis water turbine for river applications using computational fluid dynamics
Demircan, Eren; Aksel, Mehmet Haluk; Pınarcıoğlu, Mehmet Melih; Department of Mechanical Engineering (2014)
The main purpose of this study is to design a Darrieus rotor type vertical axis water turbine using Computational Fluid Dynamics (CFD) in order to be used in river currents. The CFD modeling is based on two dimensional numerical solution of the rotor motion using commercial Unsteady Reynolds Averaged Navier-Stokes solvers, Ansys Fluent and CFX. To validate the two dimensional numerical solution, an experimental Darrieus rotor type water turbine from literature is studied and performance of several turbulenc...
Optimization of aeroelastic flapping motion of thin airfoils in a biplane configuration for maximum thrust
Kaya, Mustafa; Tuncer, İsmail Hakkı; Jones, Kevin D.; Platzer, Max F. (2007-01-01)
An aeroelastic flapping motion of thin airfoils in a biplane configuration is optimized for maximum thrust. Airfoils are attached to swing arms by an elastic joint, which is model led by a torsional spring. A spring-mass system is employed for the aeroelastic coupling. The stiffness coefficient and the mass moment of inertia of the airfoil are optimized for maximum thrust. A gradient based optimization method is employed in a parallel computing environment. Unsteady, low speed flows are computed in parallel...
Citation Formats
Ç. H. Karaman, “Validation of depth-averaged mixing length turbulence model for uniform channel flows/,” M.S. - Master of Science, Middle East Technical University, 2014.