scholarly journals Large-Eddy Simulation of a microburst

2011 ◽  
Vol 11 (17) ◽  
pp. 9323-9331 ◽  
Author(s):  
V. Anabor ◽  
U. Rizza ◽  
E. L. Nascimento ◽  
G. A. Degrazia
Keyword(s):  
Large Eddy Simulation ◽  
Three Dimensional ◽  
Leading Edge ◽  
Dimensional Structure ◽  
Ring Vortex ◽  
Surface Winds ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Strong Winds ◽  
Complex Phenomena

Abstract. The three-dimensional structure and evolution of an isolated and stationary microburst are simulated using a time-dependent, high resolution Large-Eddy-Simulation (LES) model. The microburst is initiated by specifying a simplified cooling source at the top of the domain around 2 km a.g.l. that leads to a strong downdraft. Surface winds of the order of 30 m s−1 were obtained over a region of 500 m radius around the central point of the impinging downdraft, with the simulated microburst lasting for a few minutes. These characteristic length and time scales are consistent with results obtained from numerical simulations of microbursts using cloud-resolving models. The simulated flow replicated some of the principal features of microbursts observed by Doppler radars: in particular, the horizontal spread of strong surface winds and a ring vortex at the leading edge of the cold outflow. In addition to the primary surface outflow, the simulation also generated a secondary surge of strong winds that appears to represent a pulsation in the microburst evolution. These results highlight the capability of LES to reproduce complex phenomena like microbursts, indicating the potential usage of LES models to represent atmospheric phenomena of time and space scales between the convective scale and the microscale. These include short-lived convectively-generated damaging winds.

scholarly journals Numerical modelling of microburst with Large-Eddy Simulation

2010 ◽  
Vol 10 (10) ◽  
pp. 24345-24370
Author(s):  
V. Anabor ◽  
U. Rizza ◽  
G. A. Degrazia ◽  
E. de Lima Nascimento
Keyword(s):  
Large Eddy Simulation ◽  
Time Scale ◽  
Doppler Radar ◽  
Leading Edge ◽  
Ring Vortex ◽  
Short Time Scale ◽  
Eddy Simulation ◽  
Cloud Models ◽  
Large Eddy ◽  
The Impact

Abstract. An isolated and stationary microburst is simulated using a 3-D time-dependent, high resolution Large-Eddy Simulation (LES) model. The microburst downdraft is initiated by specifying a simplified cooling source at the top of the domain near 2 km. The modelled time scale for this damaging wind (30 m/s) is of order of few min with a spatial scale enclosing a region with 500 m radius around the impact point. These features are comparable with results obtained from full-cloud models. The simulated flow shows the principal features observed by Doppler radar and others observational full-scale downburst events. In particular are observed the expansion of the primary and secondary cores, the presence of the ring vortex at the leading edge of the cool outflow, and finally an accelerating outburst of surface winds. This result evidences the capability of LES to reproduce complexes phenomena like a Microburst and indicates the potential of LES for utilization in atmospheric phenomena situated below the storm scale and above the microscale, which generally involves high velocities in a short time scale.

scholarly journals Validation study for Large-Eddy Simulation of Forest Flow

2020 ◽  
Vol 207 ◽  
pp. 02010
Author(s):  
George Pitchurov ◽  
Christof Gromke ◽  
Jordan A. Denev ◽  
Flavio Cesar Cunha Galeazzo
Keyword(s):  
Wind Tunnel ◽  
Large Eddy Simulation ◽  
Forest Canopy ◽  
Turbulence Models ◽  
Leading Edge ◽  
Eddy Simulation ◽  
Sink Term ◽  
Large Eddy ◽  
Open Test ◽  
Strong Winds

The publication presents Large-Eddy Simulation (LES) of flow over a reduced-scale wind tunnel model of a forest canopy. The final aim of the study is to determine factors responsible for damage in forests by strong winds. The wind tunnel forest was represented by an open-porous foam material for the crown layer and wooden dowels for the trunk layer. The forest model was installed in the open test section of a Goettingen-type wind tunnel and Particle Image Velocimetry (PIV) measurements were made for the acquisition of the flow field data. The numerical simulations were performed with OpenFOAM®. The forest was modelled by an additional sink term in the momentum transport equations based on the leaf area density and a characteristic drag coefficient for the underlying tree specimen. Large-eddy simulations with different subgrid-scale (SGS) turbulence models were carried out and compared to wind tunnel data. The Smagorinsky SGS model outperformed the dynamic Lagrangian SGS model in the windward edge region (within a distance of approximately 2 tree heights from the leading edge) whereas the dynamic Lagrangian SGS model showed a better performance for regions farther downstream.

Analysis on the Flow Passed a Pervious Cubic-Blunt Body Based on Large Eddy Simulation

2013 ◽  
Vol 353-356 ◽  
pp. 2477-2481
Author(s):  
En Li Ye ◽  
Yi Hong Zhou ◽  
Lei Ren
Keyword(s):  
Comparative Analysis ◽  
Flow Field ◽  
Large Eddy Simulation ◽  
Vortex Shedding ◽  
Blunt Body ◽  
Static Pressure ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Eddy Simulation ◽  
Large Eddy

To overcome the deficiency that model experiments are unable to take accurate measurements without damaging the structure of the fine flow fields, a large eddy simulation is employed to simulate the three dimensional structure of the flow passed a pervious cubic-blunt body at Re=2.2×104. A comparative analysis have been taken qualitatively and quantitatively between the flow passed a pervious cubic-blunt body and the flow passed a non-pervious cubic-blunt body from the aspects of the flow structure (mainly including separation and reattachment), unsteady vortex shedding, distribution of static pressure and drag coefficient, etc. Therefore, characteristics of this kind of flow field are concluded and along with a better understanding of concrete effects they bring, which can give guidance to engineering.

Large‐Eddy Simulation of Three‐Dimensional Flow Structures Over Wave‐generated Ripples

2021 ◽  
Author(s):  
Chuang Jin ◽  
Giovanni Coco ◽  
Rafael O. Tinoco ◽  
Pallav Ranjan ◽  
Jorge San Juan ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Three Dimensional ◽  
Flow Structures ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Eddy Simulation ◽  
Large Eddy

Large Eddy Simulation of Cross Flow in Pipe Junction

2018 ◽  
Author(s):  
Jiajun Chen ◽  
Yue Sun ◽  
Hang Zhang ◽  
Dakui Feng ◽  
Zhiguo Zhang
Keyword(s):  
Large Eddy Simulation ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Cross Flow ◽  
Exciting Force ◽  
Navier Stokes ◽  
Pipe Network ◽  
Eddy Simulation ◽  
Large Eddy

Mixing in pipe junctions can play an important role in exciting force and distribution of flow in pipe network. This paper investigated the cross pipe junction and proposed an improved plan, Y-shaped pipe junction. The numerical study of a three-dimensional pipe junction was performed for calculation and improved understanding of flow feature in pipe. The filtered Navier–Stokes equations were used to perform the large-eddy simulation of the unsteady incompressible flow in pipe. From the analysis of these results, it clearly appears that the vortex strength and velocity non-uniformity of centerline, can be reduced by Y-shaped junction. The Y-shaped junction not only has better flow characteristic, but also reduces head loss and exciting force. The results of the three-dimensional improvement analysis of junction can be used in the design of pipe network for industry.

Large eddy simulation of stratified mixing in a three-dimensional lock-exchange system

2009 ◽  
Vol 26 (3-4) ◽  
pp. 134-155 ◽  
Author(s):  
Tamay M. Özgökmen ◽  
Traian Iliescu ◽  
Paul F. Fischer
Keyword(s):  
Large Eddy Simulation ◽  
Three Dimensional ◽  
Exchange System ◽  
Eddy Simulation ◽  
Large Eddy
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