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On The Effect Of Elasticity On Drag Reduction Due To Polymer Additives Using A Hybrid D.N.S. And Langevin Dynamics Approach, Arnout Boelens
On The Effect Of Elasticity On Drag Reduction Due To Polymer Additives Using A Hybrid D.N.S. And Langevin Dynamics Approach, Arnout Boelens
Open Access Dissertations
In this work the effect of elasticity on turbulent drag reduction due to polymers is investigated using a hybrid Direct Numerical Simulation (D.N.S) and Langevin dynamics approach. Simulations are run at a friction Reynolds number of Re_&tau = 560 for 960.000 dumbbells with Deborah numbers of De = 0, De = 1, and De = 10. The conclusions are that it is possible to simulate a drag reduced flow using hybrid D.N.S. with Langevin dynamics, that polymers, like other occurrences of drag reduction, reduce drag through streak stabilization, and that the essential property of polymers and fibers in having a …
A Study On Small Scale Intermittency Using Direct Numerical Simulation Of Turbulence, Saba Almalkie
A Study On Small Scale Intermittency Using Direct Numerical Simulation Of Turbulence, Saba Almalkie
Open Access Dissertations
Theory of turbulence at small scales plays a fundamental role in modeling turbulence and in retrieving information from physical measurements of turbulent flows. A systematic methodology based on direct numerical simulations of turbulent flows is developed to investigate universality of small scale turbulence. Understanding characteristics of the small scale intermittency in turbulent flows and the accuracy of the models, measurements, and theories in predicting it are the main objectives. The research is designed to address two central questions; 1) possible effects of large scale anisotropies on the small scale turbulence and 2) potential biases in characterizing small scale turbulence due …
The Oriented-Eddy Collision Model, Michael Bernard Martell Jr.
The Oriented-Eddy Collision Model, Michael Bernard Martell Jr.
Open Access Dissertations
The physical and mathematical foundations of the Oriented-Eddy Collision turbulence model are provided through a discussion of the Reynolds averaged Navier-Stokes (RANS) equations, probability density functions (PDF), PDF collision models, Reynolds stress transport models (RSTM), and two-point correlations. Behavior of the Oriented-Eddy Collision turbulence model near solid boundaries is examined in depth. The Oriented-Eddy Collision turbulence model treats turbulence in a novel way: the average behavior of a turbulent flow can be modeled as a collection of interacting fluid particles, or eddies, which have inherent orientation. The model is cast in the form of a collection of Reynolds stress transport …