scholarly journals Three-dimensional instabilities and negative eddy viscosity in thin-layer flows

2018 ◽  
Vol 3 (11) ◽  
Author(s):  
Alexandros Alexakis
Keyword(s):  
Thin Layer ◽  
Eddy Viscosity ◽  
Three Dimensional

Microstructures of Low Angle Boundaries of the Second Generation Single Crystal Superalloy DD6

2011 ◽  
Vol 284-286 ◽  
pp. 1584-1587
Author(s):  
Zhen Xue Shi ◽  
Jia Rong Li ◽  
Shi Zhong Liu ◽  
Jin Qian Zhao
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Thin Layer ◽  
Single Crystal ◽  
Second Generation ◽  
Three Dimensional ◽  
Single Crystal Superalloy ◽  
Transition Electron ◽  
Scanning Electron

The specimens of low angle boundaries were machined from the second generation single crystal superalloy DD6 blades. The microstructures of low angle boundaries (LAB) were investigated from three scales of dendrite, γ′ phase and atom with optical microscopy (OM), scanning electron microscope (SEM), transition electron microscope (TEM) and high resolution transmission electrion microscopy (HREM). The results showed that on the dendrite scale LAB is interdendrite district formed by three dimensional curved face between the adjacent dendrites. On the γ′ phase scale LAB is composed by a thin layer γ phase and its bilateral imperfect cube γ′ phase. On the atom scale LAB is made up of dislocations within several atom thickness.

An Assessment of Three-Dimensional Turbulent Boundary Layer Prediction Methods

1973 ◽  
Vol 95 (3) ◽  
pp. 415-421 ◽  
Author(s):  
A. J. Wheeler ◽  
J. P. Johnston
Keyword(s):  
Boundary Layer ◽  
Eddy Viscosity ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Boundary Layer Flows ◽  
Mean Velocity ◽  
Eddy Viscosity Model ◽  
Separating Flow ◽  
Dimensional Boundary ◽  
Stress Models

Predictions have been made for a variety of experimental three-dimensional boundary layer flows with a single finite difference method which was used with three different turbulent stress models: (i) an eddy viscosity model, (ii) the “Nash” model, and (iii) the “Bradshaw” model. For many purposes, even the simplest stress model (eddy viscosity) was adequate to predict the mean velocity field. On the other hand, the profile of shear stress direction was not correctly predicted in one case by any model tested. The high sensitivity of the predicted results to free stream pressure gradient in separating flow cases is demonstrated.

Fabrication of thin-layer matrigel-based constructs for three-dimensional cell culture

2018 ◽  
Vol 35 (1) ◽  
pp. e2733 ◽  
Author(s):  
Kristin Robin Ko ◽  
Meng-Chiao Tsai ◽  
John P. Frampton
Keyword(s):  
Cell Culture ◽  
Thin Layer ◽  
Three Dimensional ◽  
Dimensional Cell

Thin-layer approximation for three-dimensional supersonic corner flows

AIAA Journal ◽  
1980 ◽  
Vol 18 (12) ◽  
pp. 1544-1546 ◽  
Author(s):  
C. M. Hung ◽  
Seth S. Kurasaki
Keyword(s):  
Thin Layer ◽  
Three Dimensional ◽  
Thin Layer Approximation ◽  
Corner Flows

Simple eddy viscosity relations for three-dimensional turbulent boundary layers

AIAA Journal ◽  
1977 ◽  
Vol 15 (6) ◽  
pp. 886-887 ◽  
Author(s):  
George L. Mellor ◽  
H. James Herring
Keyword(s):  
Boundary Layers ◽  
Eddy Viscosity ◽  
Three Dimensional ◽  
Turbulent Boundary Layers

Performance of eddy-viscosity-based turbulence models in three-dimensional turbulent interaction

AIAA Journal ◽  
1996 ◽  
Vol 34 (4) ◽  
pp. 844-847 ◽  
Author(s):  
Datta Gaitonde ◽  
J. S. Shang ◽  
J. R. Edwards
Keyword(s):  
Eddy Viscosity ◽  
Three Dimensional ◽  
Turbulence Models

Turbulence and mixing in unsteady breaking surface waves

2009 ◽  
Vol 628 ◽  
pp. 85-119 ◽  
Author(s):  
DAVID A. DRAZEN ◽  
W. KENDALL MELVILLE
Keyword(s):  
Eddy Viscosity ◽  
Particle Image ◽  
Three Dimensional ◽  
Image Data ◽  
Mean Velocity ◽  
Indirect Methods ◽  
Local Maxima ◽  
High Resolution Imagery ◽  
Image Velocimetry ◽  
Direct And Indirect Methods

Laboratory measurements of the post-breaking velocity field due to unsteady deep-water breaking are presented. Digital particle image velocimetry (DPIV) is used to measure the entire post-breaking turbulent cloud with high-resolution imagery permitting the measurement of scales fromO(1m) down toO(1mm). Ensemble-averaged quantities including mean velocity, turbulent kinetic energy (TKE) density and Reynolds stress are presented and compare favourably with the results of Melville, Veron & White (J. Fluid Mech., vol. 454, 2002, pp. 203–233; MVW). However, due to limited resolution, MVW's measurements were not spatially coherent across the turbulent cloud, and this restricted their ability to compute turbulent wavenumber spectra. Statistical spatial quantities including the integral length scaleL11, Taylor microscale λfand the Taylor microscale Reynolds numberReλare presented. Estimation of an eddy viscosity for the breaking event is also given based on analysis of the image data. Turbulent wavenumber spectra are computed and within 12 wave periods after breaking exhibit what have been termed ‘spectral bumps’ in the turbulence literature. These local maxima in the spectra are thought to be caused by an imbalance between the transport of energy from large scales and the dissipation at small scales. Estimates of the dissipation rate per unit mass are computed using both direct and indirect methods. Horizontally averaged terms in the TKE budget are also presented up to 27 wave periods after breaking and are discussed with regard to the dynamics of the post-breaking flow. Comparisons of the TKE density in the streamwise and cross-stream planes with the three-dimensional full TKE density are given in an appendix.

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