Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 41 for “"Transition to turbulence"”.
-
Transition to turbulence and relaminarization of pulsatile pipe flows
<p>The instability and transition to turbulence and its evolution in pulsatile pipe flows involving both, reverse and no-reverse flows, is the primary focus of this experimental work. A piston driven by a programable DC servo motor was used to set up a water flow system and provide the pulsation …
-
Instability and Transition to Turbulence in Complex Viscoelastic Flows Overlying Porous Surfaces
… Darcy-Brinkman-Oldroyd-B model is developed to describe the flow behavior within and adjacent to porous media, incorporating fully coupled interfacial conditions between the free-fluid and porous domains. Using this framework, a comprehensive linear stability analysis is conducted for plane …
-
Heat transfer at transition to turbulence in channel flows with eddy promoters
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994.
-
An experimental investigation of the transition to turbulence of the thermal convective flow in air between horizontal plates.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1971.
-
Investigation of transition to turbulence at low Reynolds numbers using Implicit Large Eddy Simulations with a Discontinuous Galerkin method
… bubbles at low Reynolds numbers and the related transition to turbulence. In addition to being one of the first Implicit Large Eddy Simulation studies using a high-order Discontinuous Galerkin method, unique attention is given to the boundary layer characteristics thus contributing to the …
-
Coherent structures in incompressible fluid flows
The work is broadly related to the transition to turbulence in pipe at intermediate Reynolds numbers and includes a discussion of two classes of structures observed during the transition to turbulence: numerically-extracted solutions of the Navier-Stokes equations (the "exact'') and …
-
High-order implicit large-eddy simulation for transitional aerodynamics flows
… Simulation (ILES) approach for simulating transitional aerodynamic flows. The approach consists of a hybridized Discontinuous Galerkin (DG) method for the discretization of the Navier-Stokes (NS) equations and a parallel preconditioned Newton-GMRES solver for the resulting nonlinear system …
-
An adaptive high order Reynolds-averaged Navier-Stokes solver with transition prediction
… order accurate, which makes them unfeasible to resolve multi-scale phenomena such as turbulence or acoustics, and limits their efficiency in terms of the error per degree of freedom. In recent years, the CFD community has put significant effort into the development of high order methods for …
-
Wave interactions in three-dimensional boundary layers
… self-interaction of primary instabilities in the transition-to-turbulence process in three-dimensional boundary layers are investigated. Resonant triad interactions are studied in the boundary layer on the leading edge of a swept wing under typical commercial jet cruise conditions. Both …
-
Numerical studies of the flow around an airfoil at low Reynolds number
… Initially volume forcing is introduced in order to promote transition to turbulence. After obtaining sufficient data from this forced case, the explicitly added disturbances are removed and the simulation run further. With no forcing the turbulence is observed to 'self-sustain', with increased …
-
Simulation of Turbulent Flows Using Nodal Integral Method
The PMNIM is then used to study the transition to turbulence in Arnold-Beltrami-Childress (ABC) flows. These flows display the interesting phenomenon of heteroclinic cycles. The results are obtained for two wavenumbers: k = 1 (also studied earlier by other researchers) and k = 2, respectively. The …
-
The nonlinear evolution of secondary instabilities in boundary layers
… a study is made of the pre-breakdown stage of transition to turbulence in boundary layers. The first step consists of a ’decoupling’ of the primary and secondary instabilities. A perturbation method is used to solve for the primary wave, in the absence of any secondary disturbances. Once the …
-
Sensitivity Analysis of Partial Differential Equations With Applications to Fluid Flow
For over 100 years, researchers have attempted to predict transition to turbulence in fluid flows by analyzing the spectrum of the linearized Navier-Stokes equations. However, for many simple flows, this approach has failed to match experimental results. Recently, new scenarios for transition have …
-
Flow over large-scale low-order topographies: impact of heterogeneities
… experimental investigation was carried out to provide phenomenological and quantitative insight on the flow over large-scale topographies characterized by few dominant modes. Particle image velocimetry (PIV) was used in a refractive-index-matching (RIM) channel to study the dynamics of the …
-
Generalised nonlinear stability of stratified shear flows: adjoint-based optimisation, Koopman modes, and reduced models
… plane Couette flow. I begin by describing the history of transient growth phenomena, and in particular the recent application of adjoint based optimisation to find nonlinear optimal perturbations and associated minimal seeds for turbulence, the smallest amplitude perturbations that are able to …
-
Observation and Measurement of the Growth of the Primary Instabilities of the Richtmyer-Meshkov Instability and Observation of Secondary Instabilities
… column of sulfur hexafluoride saturated with acetone. The experimental study is performed at two Mach numbers, 1.7 and 2.1, both with a maximum variation of 10% of either Mach number. The measurements of the size of these features of interest were compared to two external characteristics of the …
-
Nonlinear and non-modal stability of structures evolving in shear flows
… explores a range of stability techniques applied to fluid structures that develop in various constant density flows. In particular, the stability of nonlinear structures which develop in rotating plane Couette flow is analyzed using Floquet theory, which allows the global stability of an important …
-
The effects of variation in wave period and flow asymmetry in sediment dynamics
The results of laboratory experiments are described, relating to aspects of hydrodynamics and sediment dynamics under second-order Stokes type waves (or flows), of varying degrees of asymmetry. The majority of the measurements related to laminar and/or transitional flow conditions and were made …
-
Dynamics of stochastic spatial-temporal patterns in transitional turbulence
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2026-12-01
-
Incompressible flow over a three-dimensional cavity
… a solid surface. This study has been divided into two parts: 1) incompressible laminar flow passing over a three-dimensional cavity; and 2) incompressible laminar-to-turbulent transition over a three-dimensional cavity.<br/><br/>In the second part, a CFD code for the solution of the …
Page 1 of 3