Numerical simulations of impinging jets with application to downbursts

Kim, Jong-Dae; Hangan, Horia

doi:10.1016/j.jweia.2006.07.002

Cited by 177 publications

(118 citation statements)

References 24 publications

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“…The most common of these is the impinging jet simulator, either constructed in a laboratory, for example Holmes (1992) and Xu and Hangan (2008) or modelled numerically, for example (Selvam and Holmes, 1992) and Kim and Hangan (2007). These models can then be scaled to the limited full scale data and then model buildings placed in the flow with the resulting pressure fields analysed (although there are difficulties with selecting appropriate scaling for the simulations).…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of the flow field around low rise buildings due to a downburst event using large eddy simulation

Haines

Taylor

2018

Journal of Wind Engineering and Industrial Aerodynamics

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The transient lift and drag coefficients around a low rise cube of dimension 60mm and a portal building of dimensions 240 Â 130 Â 53mm with eaves height of 42mm, which arise from the numerical simulation of an impinging jet or downburst are investigated. The numerical results were validated against a experimental results from a laboratory impinging jet simulator operating at the same scale. Having found the CFD simulation to match well with the laboratory scale the CFD was then used to visualise and interpret the flow field around the buildings. Common transient atmospheric boundary layer flow features, such as conical vortices, vortices on the rear face of a building, flow separation and vortex shedding were observed and could be used to explain the lift and drag results obtained. In particular, motion of the primary vortex from the downburst and its effect on the transient pressures on the building were identified, with strong pressure gradients observed for a number of configurations. Aspects of the flow phenomena were identified, which along with the strong pressure changes on the building surfaces, indicate areas of further research due to their potential impact on building and cladding design.

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Section: Introductionmentioning

confidence: 99%

Numerical investigation of the flow field around low rise buildings due to a downburst event using large eddy simulation

Haines

Taylor

2018

Journal of Wind Engineering and Industrial Aerodynamics

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“…In the context of numerical modelling of microbursts with engineering applications some recent studies include that of Nicholls et al (1993), which performed a 2-D very high resolution simulation of a microburst on a building model. Kim and Hangan (2007) Sub-cloud numerical simulations of microbursts not including cloud microphysics nor large scale atmospheric processes can be performed at very high resolution, allowing the analysis of detailed structure of the near-ground flow dynamics, where the strongest wind speeds are usually detected in microbursts. The thermal forcing for these simulations is usually parameterized using a spatio-temporal variable function that is decoupled from microphysics and moisture advection (Orf et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

Large-Eddy Simulation of a microburst

et al. 2011

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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 convectivelygenerated damaging winds.

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“…The number of elements of a set has at least 35% more than any of the other sets. Grid resolution for all the meshes used for the present mesh convergence study are higher than any of the previously published numerical simulations [22,28,34]. Details of the meshes are summarized in Table 1.…”

Section: Grid Convergencementioning

confidence: 99%

“…Apart from the impinging jet, other models, such as the 'cooling source' approach, as proposed by Anderson et al [23] and meteorological full or sub-cloud modelling techniques, as demonstrated by Orf et al [24][25][26] and Vermeire et al [27], have been used previously to emulate downburst wind shear in laboratories, or in numerical simulations. The benefits of the impinging jet modelling approach, when compared to the other approaches, is a much lower computational cost and its ability to model the macro dynamics of downburst [28]. Note that a steady impinging jet model does not have the same meteorological processes (i.e., density stratification of the atmosphere and buoyancy-induced turbulence), transient behaviour and Reynolds number observed in a real full-scale microburst.…”

Section: Introductionmentioning

confidence: 99%

“…For numerical Computational Fluid Dynamics (CFD) studies, both unsteady and steady numerical Reynolds-averaged Navier-Stokes (URANS and RANS) simulations have been conducted by Chay et al [30], Kim and Hangan [28], Li et al [31] and Zhang et al [22]. A combination of numerical and experimental work of steady impinging jet flow can be found in the work of Wood et al [32], Sengupta and Sarkar [33], Xu and Hangan [29], and Das et al [34].…”

Section: Introductionmentioning

confidence: 99%

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Temporal Variation of the Pressure from a Steady Impinging Jet Model of Dry Microburst-Like Wind Using URANS

Skote

Sim

Srikanth³

2018

Computation

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Abstract:The objective of this study is to investigate the temporal behavior of the pressure field of a stationary dry microburst-like wind phenomenon utilizing Unsteady Reynolds-averaged Navier-Stokes (URANS) numerical simulations. Using an axisymmetric steady impinging jet model, the dry microburst-like wind is simulated from the initial release of a steady downdraft flow, till the time after the primary vortices have fully convected out of the stagnation region. The validated URANS results presented herein shed light on the temporal variation of the pressure field which is in agreement with the qualitative description obtained from field measurements. The results have an impact on understanding the wind load on structures from the initial touch-down phase of the downdraft from a microburst. The investigation is based on CFD techniques, together with a simple impinging jet model that does not include any microphysical processes. Unlike previous investigations, this study focuses on the transient pressure field from a downdraft without obstacles.

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Numerical simulations of impinging jets with application to downbursts

Cited by 177 publications

References 24 publications

Numerical investigation of the flow field around low rise buildings due to a downburst event using large eddy simulation

Numerical investigation of the flow field around low rise buildings due to a downburst event using large eddy simulation

Large-Eddy Simulation of a microburst

Temporal Variation of the Pressure from a Steady Impinging Jet Model of Dry Microburst-Like Wind Using URANS

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