Tracking of large-scale structures in turbulent channel with direct numerical simulation of low Prandtl number passive scalar

2014 ◽  
Vol 26 (12) ◽  
pp. 125111 ◽  
Author(s):  
Iztok Tiselj
Keyword(s):  
Numerical Simulation ◽  
Prandtl Number ◽  
Direct Numerical Simulation ◽  
Large Scale ◽  
Passive Scalar ◽  
Large Scale Structures ◽  
Scale Structures

Large-scale structures in stratified turbulent Couette flow and optimal disturbances

2020 ◽  
Vol 35 (1) ◽  
pp. 37-53
Author(s):  
Grigory V. Zasko ◽  
Andrey V. Glazunov ◽  
Evgeny V. Mortikov ◽  
Yuri M. Nechepurenko
Keyword(s):  
Numerical Simulation ◽  
Couette Flow ◽  
Large Scale ◽  
Spatial Scales ◽  
Static Stability ◽  
Simulation Data ◽  
Direct Numerical Simulation Data ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Optimal Disturbances

AbstractDirect numerical simulation data of a stratified turbulent Couette flow contains two types of organized structures: rolls arising at neutral and close to neutral stratifications, and layered structures which manifest themselves as static stability increases. It is shown that both types of structures have spatial scales and forms that coincide with the scales and forms of the optimal disturbances of the simplified linear model of the Couette flow with the same Richardson numbers.

A Review on Numerical Simulation of Pile Caps in Large-Scale Structures

2011 ◽  
Vol 94-96 ◽  
pp. 131-135
Author(s):  
Jian Jiang Yang ◽  
Rui Wang ◽  
Bo Zhou
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Theoretical Research ◽  
Water Tank ◽  
Large Scale Structures ◽  
Advantages And Disadvantages ◽  
Pile Caps ◽  
Force Mode ◽  
Scale Structures ◽  
Force Mechanism

Cap plays a transitional role in the structure. It is an important part to ensure the effective pass of load between the upper structure and the foundation. In the bridge, water tank, ocean platforms, oil tank and other large-scale structures, the force mechanism and force mode about cap are more and more valued by researchers. The research method about large cap structure mainly includes theoretical research, experimental research, numerical simulation and other aspects. This article summarizes the domestic research status, reviews and compares the caps’ numerical simulation methods and analyzes the advantages and disadvantages of different models. Finally, some problems are proposed for further research, which can provide references for engineering design and study.

Numerical Simulation of Unsteady Turbulent Flow in Axisymmetric Sudden Expansions

2001 ◽  
Vol 123 (3) ◽  
pp. 574-587 ◽  
Author(s):  
Baoyu Guo ◽  
Tim A. G. Langrish ◽  
David F. Fletcher
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flows ◽  
Large Scale ◽  
Critical Value ◽  
Expansion Ratio ◽  
Large Scale Structures ◽  
Inlet Swirl ◽  
Scale Structures ◽  
Reported Data ◽  
Oscillation Frequencies

This paper is concerned with the numerical simulation of unsteady turbulent flows behind sudden expansions without inlet swirl. Time dependent simulations have been carried out using the VLES approach with the standard k-ε model. The expansion ratio investigated is in the range from 1.96–6.0. The simulations show that the flows in axisymmetric sudden expansions are inherently unstable when the expansion ratio is above a critical value. The precessing phenomenon, which features self-sustained precession of the global flowfield around the expansion centerline, is predicted successfully using CFD, with simulated oscillation frequencies that are in general agreement with reported data. For the case of expansion ratios from 3.5–6.0, a combination of a precession motion and a flapping motion in a rotating frame of reference is predicted in terms of the jet movement. Large-scale structures are identified in the downstream flowfield. Other important phenomena, such as the transition of the oscillation patterns, have also been predicted.

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

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