Large-Eddy Simulation of a Tornado’s Interaction with the Surface

Lewellen, W. S.; Lewellen, D. C.; Sykes, R. I.

doi:10.1175/1520-0469(1997)054<0581:lesoat>2.0.co;2

Cited by 155 publications

(102 citation statements)

References 16 publications

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“…Evolution of the tornado structure appears to be sensitive to S. When S is relatively large, the central downdraft intensifies, and the tornado evolves into a multiple-vortex structure. Although the value of S is quite large, this result is qualitatively consistent with those of the previous laboratory experiments (e.g., Church et al 1979;DaviesJones 1986) and idealized numerical simulations (e.g., Rotunno 1979; Lewellen et al 1997;Nolan et al 2017). It was confirmed that the results are robust even if V θ and W 0 are calculated by using R 0 = 200 m at a height of 250 m. …”

Section: Multiple-vortex Structuresupporting

confidence: 89%

“…4c). While the tornado exhibited a multiple-vortex structure, strong updrafts persisted at the vortex center near the surface (the central downdraft does not reach the ground), which differs from the result of the previous laboratory experiments and idealized simulations using LES (e.g., Davies-Jones 1986; Lewellen et al 1997).…”

Section: Super High-resolution Simulation Of the 6 May 2012 Tsukuba Scontrasting

confidence: 82%

“…Thus, the simulated tornado evolved from a one-cell to a two-cell structure, and subsequently exhibited a multiple-vortex structure. Such a transition of the vortex structure was also observed in previous laboratory experiments (Ward 1972;Church et al 1979), idealized simulations using LES (e.g., Rotunno 1979;Lewellen et al 1997), and observational studies (e.g., Wurman 2002, Lee and Wurman 2005, Wurman et al 2014). The multiple-vortex structure was most distinct at about 26 m height and became obscure above 200 m height.…”

Section: Super High-resolution Simulation Of the 6 May 2012 Tsukuba Ssupporting

confidence: 79%

“…5 remained almost stationary with respect to the tornado, which was moving east-northeastward, and split in two subvortices (A and D). Subvortices B, C, and D cyclonically rotated around the tornado center at a speed less than half the maximum tangential velocity of the tornado vortex, which is consistent with the laboratory experiment (Ward 1972) and idealized numerical studies (Lewellen et al 1997). The movement of these subvortices is somewhat reminiscent of a trochoidal motion of subvortices observed by Doppler radar (Wurman et al 2014) and the damage path associated with a suction vortex (Fujita 1971).…”

Section: Super High-resolution Simulation Of the 6 May 2012 Tsukuba Ssupporting

confidence: 77%

“…However, an observation of near-surface wind fields within a tornado vortex is quite rare and has offered only fragmentary information. Previous laboratory experiments (Ward 1972;Church et al 1979) and highly idealized numerical studies using large eddy simulation (LES) (e.g., Rotunno 1979;Lewellen et al 1997) have shown that a tornado-like vortex exhibits various types of structure, such as a one-cell vortex containing a single updraft, a two-cell vortex exhibiting a downdraft at the vortex center, and multiple vortices. However, the extent to which the reproduced vortex in these studies can be applied to an actual tornado is open to further discussion.…”

Section: Introductionmentioning

confidence: 99%

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Super High-Resolution Simulation of the 6 May 2012 Tsukuba Supercell Tornado: Near-Surface Structure and Its Evolution

Mashiko¹,

Niino

2017

SOLA

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A super high-resolution simulation of the 6 May 2012 Tsukuba supercell tornado with a horizontal grid spacing of 10 m is conducted to investigate its fine-scale structure under realistic environmental conditions including surface friction. The simulated tornado repeatedly exhibits evolutions from one-cell to two-cell vortex, and subsequently to a multiple-vortex structure, where the vortex structure is sensitive to a swirl ratio. Subvortices in the multiple-vortex structure are located on the immediate inside of the radius of the maximum tangential wind speed, and cyclonically rotate around the tornado center with a slower speed less than half of the maximum tangential wind speed. The subvortices have a feature of a suction vortex accompanied by strong horizontal convergence and strong updraft near the surface. Although a superposition of the swirling winds associated with the subvortices and the parent tornado vortex causes locally intensified winds, the maximum horizontal and upward winds over the tornado's lifetime occur at the stage of shrinking of the vortex radius right before a transition to a multiple-vortex structure.(Citation: Mashiko, W., and H. Niino, 2017: Super highresolution simulation of the 6 May 2012 Tsukuba supercell tornado: Near-surface structure and its evolution. SOLA, 13, 135− 139,

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Section: Multiple-vortex Structuresupporting

confidence: 89%

Section: Super High-resolution Simulation Of the 6 May 2012 Tsukuba Scontrasting

confidence: 82%

Section: Super High-resolution Simulation Of the 6 May 2012 Tsukuba Ssupporting

confidence: 79%

Section: Super High-resolution Simulation Of the 6 May 2012 Tsukuba Ssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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Super High-Resolution Simulation of the 6 May 2012 Tsukuba Supercell Tornado: Near-Surface Structure and Its Evolution

Mashiko¹,

Niino

2017

SOLA

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Analysis of the horizontal two‐dimensional near‐surface structure of a winter tornadic vortex using high‐resolution in situ wind and pressure measurements

Kato

Kusunoki²,

Satô³

et al. 2015

JGR Atmospheres

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The horizontal two-dimensional near-surface structure of a tornadic vortex within a winter storm was analyzed. The tornadic vortex was observed on 10 December 2012 by the high-resolution in situ observational linear array of wind and pressure sensors (LAWPS) system in conjunction with a high-resolution Doppler radar. The 0.1 s maximum wind speed and pressure deficit near the ground were recorded as 35.3 m s À1 and À3.8 hPa, respectively. The horizontal two-dimensional distributions of the tornadic vortex wind and pressure were retrieved by the LAWPS data, which provided unprecedented observational detail on the following important features of the near-surface structure of the tornadic vortex. Asymmetric convergent inflow toward the vortex center existed. Total wind speed was strong to the right and rear side of the translational direction of the vortex and weak in the forward part of the vortex possibly because of the strong convergent inflow in that region. The tangential wind speed profile of the vortex was better approximated using a modified Rankine vortex rather than the Rankine vortex both at 5 m above ground level (agl) and 100 m agl, and other vortex models (Burgers-Rott vortex and Wood-White vortex) were also compared. The cyclostrophic wind balance was violated in the core radius R 0 and outside the core radius in the forward sector; however, it was held with a relatively high accuracy of approximately 14% outside the core of the vortex in the rearward sector (from 2 R 0 to 5 R 0 ) near the ground.

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Advanced Topics

2022

Computational Fluid Dynamics for Wind Engineering

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Large-Eddy Simulation of a Tornado’s Interaction with the Surface

Cited by 155 publications

References 16 publications

Super High-Resolution Simulation of the 6 May 2012 Tsukuba Supercell Tornado: Near-Surface Structure and Its Evolution

Super High-Resolution Simulation of the 6 May 2012 Tsukuba Supercell Tornado: Near-Surface Structure and Its Evolution

Analysis of the horizontal two‐dimensional near‐surface structure of a winter tornadic vortex using high‐resolution in situ wind and pressure measurements

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