TURBULENCE CHARACTERISTICS OF WIND FLOW AT GROUND LEVEL IN BUILT-UP AREA

1984 ◽  
pp. 133-144
Author(s):  
Shuzo Murakami ◽  
Kunio Fujii
Keyword(s):  
Ground Level ◽  
Wind Flow ◽  
Turbulence Characteristics

An Immersed Boundary Method for Simulation of Wind Flow Over Complex Terrain

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
S. Jafari ◽  
N. Chokani ◽  
R. S. Abhari
Keyword(s):  
Immersed Boundary Method ◽  
Complex Terrain ◽  
Stokes Equations ◽  
Ground Level ◽  
Rectangular Domain ◽  
Immersed Boundary ◽  
Test Case ◽  
Wind Flow ◽  
Wall Functions ◽  
Boundary Method

The accurate modeling of the wind resource over complex terrain is required to optimize the micrositing of wind turbines. In this paper, an immersed boundary method that is used in connection with the Reynolds-averaged Navier–Stokes equations with k-ω turbulence model in order to efficiently simulate the wind flow over complex terrain is presented. With the immersed boundary method, only one Cartesian grid is required to simulate the wind flow for all wind directions, with only the rotation of the digital elevation map. Thus, the lengthy procedure of generating multiple grids for conventional rectangular domain is avoided. Wall functions are employed with the immersed boundary method in order to relax the stringent near-wall grid resolution requirements as well as to allow the effects of surface roughness to be accounted for. The immersed boundary method is applied to the complex terrain test case of Bolund Hill. The simulation results of wind speed and turbulent kinetic energy show good agreement with experiments for heights greater than 5 m above ground level.

scholarly journals Turbulence Characteristics of Wind Flow over Complex Terrain : Effects of topography on velocity correlation

2004 ◽  
Vol 2004 (0) ◽  
pp. 176
Author(s):  
Yusuke MAJIMA ◽  
Yutaka HASEGAWA ◽  
Hiroshi IMAMURA ◽  
Koji KIKUYAMA ◽  
Hitoshi SUZUKI
Keyword(s):  
Complex Terrain ◽  
Wind Flow ◽  
Velocity Correlation ◽  
Turbulence Characteristics ◽  
Terrain Effects

Computational fluid dynamics simulation and full-scale experimental model inter-comparison of the wind flow around a university campus

2016 ◽  
Vol 41 (1) ◽  
pp. 43-54
Author(s):  
AZ Dhunny ◽  
F Toja-Silva ◽  
C Peralta ◽  
MR Lollchund ◽  
SDDV Rughooputh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulence Models ◽  
Ground Level ◽  
Dynamics Simulation ◽  
Wind Flow ◽  
University Campus ◽  
Computational Fluid Dynamics Simulation ◽  
Mean Differences ◽  
The University

In this article, results obtained from two computational fluid dynamics solvers, WindSim and OpenFOAM, have been compared for the wind flow around the University of Mauritius’ campus for different wind directions, and a reference incident wind speed at diverse height above ground level. A grid resolution study is performed for both software and the mean differences of the two solvers with multiple turbulence models (standard k-ε, k-ε with Yap correction, and renormalization group k-ε) are analyzed with onsite measured data. The article concludes that the best results for the computational fluid dynamics simulation of the wind flow around buildings are obtained using OpenFOAM with k-ε turbulence model including Yap correction.

scholarly journals Mean flow and turbulence characteristics of a nocturnal downburst recorded on a 213 m tall meteorological tower

2021 ◽  
Author(s):  
Djordje Romanic
Keyword(s):  
Surface Roughness ◽  
Wind Direction ◽  
Friction Velocity ◽  
Similarity Theory ◽  
Ground Level ◽  
Velocity Profiles ◽  
Secondary Vortex ◽  
Mean Flow ◽  
Measured Velocity ◽  
Turbulence Characteristics

AbstractThis study presents rare measurements and analysis of a nocturnal thunderstorm downburst on the 213 m tall Cabauw tower in The Netherlands. The event occurred on 12 March 2008 between 02:00 and 03:00 UTC and was measured using four ultrasonic 10-Hz anemometers positioned at 3, 60, 100, and 180 m above ground level. 1-second gusts in the outflow exceeded 30 m s−1 at 60 m and above. This wind event was accompanied by an abrupt change of wind direction from southwest to west. While the shift in wind direction corresponded with the change of upwind surface roughness, the time series of turbulence intensity and other turbulence characteristics were not affected. The statistical properties of this event were compared against the largest European database of thunderstorm winds measured in the Mediterranean. The study also demonstrated that primary and secondary vortex structures—secondary vortex being rarely observed in actual downbursts—developed at the forward edge of the cold outflow. The estimated diameter of the downdraft was 1200 m at 70 m above ground. The measured velocity profiles and friction velocity were compared against theoretical predictions of the Monin-Obukhov Similarity Theory (MOST). MOST without stratification adjustment overestimated measured friction velocity twofold. Alternative values for surface roughness during the outflow were derived based on the measured friction velocity and MOST-based fit of measured velocity profiles. Ceilometer and radar measurements were supplementary data in this analysis.

Effects of Vibration on the Preparation of Ultrathin Sections

1973 ◽  
Vol 31 ◽  
pp. 358-359
Author(s):  
Joseph M. Blum ◽  
Edward P. Gargiulo ◽  
J. R. Sawers
Keyword(s):  
Cutting Speed ◽  
Ground Level ◽  
Environmental Vibration ◽  
Block Face ◽  
Ultrathin Sections ◽  
Embedding Medium ◽  
Thickness Variations ◽  
Building Walls ◽  
Cutting Direction ◽  
Diamond Knife

It is now well-known that chatter (Figure 1) is caused by vibration between the microtome arm and the diamond knife. It is usually observed as a cyclical variation in “optical” density of an electron micrograph due to sample thickness variations perpendicular to the cutting direction. This vibration might be induced by using too large a block face, too large a clearance angle, excessive cutting speed, non-uniform embedding medium or microtome vibration. Another prominent cause is environmental vibration caused by inadequate building construction. Microtomes should be installed on firm, solid floors. The best floors are thick, ground-level concrete pads poured over a sand bed and isolated from the building walls. Even when these precautions are followed, we recommend an additional isolation pad placed on the top of a sturdy table.

A global perspective of ground level, 'ambient' carbon dioxide for assessing the response of plants to atmospheric CO2

2001 ◽  
Vol 7 (7) ◽  
pp. 789-796 ◽  
Author(s):  
L. H. Ziska ◽  
O. Ghannoum ◽  
J. T. Baker ◽  
J. Conroy ◽  
J. A. Bunce ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ground Level ◽  
Global Perspective ◽  
Atmospheric Co2
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