A numerical study of flow fields of lobed hailstones falling in air

Wang, Pao K.; Chueh, Chih‐Che; Wang, Chen Kang

doi:10.1016/j.atmosres.2015.02.013

Cited by 10 publications

(26 citation statements)

References 12 publications

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“…The length of the lobes in the configuration with the long lobes is 20 % of the maximum dimension and for the short lobed ones it is 10 %. Thus, similar to Wang et al [12] we were able to investigate the influence of the number and size of the lobes on the fall behavior. Additionally to the lobed hailstones also spheres were printed for comparison.…”

Section: Hail Productionmentioning

confidence: 63%

“…Lobed hailstones were produced using 3D printing technology based on mathematical formulations given in Wang et al [12]. From Equations ( 1) to (3) in that study stl-files (stl:= Surface Triangle Language) representing the 3D surface of hailstones were created using the build-in function of Wolframs Mathematica software package.…”

Section: Hail Productionmentioning

confidence: 99%

“…Further, they revealed for all categories a decreasing behavior for increasing Reynolds numbers Re. The present study is aimed to experimentally investigate the influence of lobes on the aerodynamic behavior of hailstones, similar to the study of Wang et al [12]. Specifically, four of the six hailstone categories used in Wang et al [12] were printed with the 3D printing technology and tested on their drag coefficient and terminal velocity in the Mainz vertical wind tunnel.…”

Section: Introductionmentioning

confidence: 98%

“…Wang and Chueh [11] found that the ventilation effect for large lobed hailstones is increased by a factor of up 2.5 compared to spheres of the same size. The developing lobes in turn affect the flow field around the hailstones (e.g., Wang et al [12] and Cheng and Wang [13]), and thus their fall characteristics such as drag coefficient, terminal velocity, and fall behavior.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, a correct understanding of the influence of lobes on the fall properties of hailstones such as fall mode, terminal velocity and drag coefficient is crucial to reliably simulate the growth of hailstones with numerical models. Wang et al [12] performed numerical simulations on the flow fields around lobed hailstones to investigate their influence on the drag coefficient. For that purpose they tested six hailstone categories with different surface properties which are based on mathematical formulations.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

A Wind Tunnel Investigation into the Aerodynamics of Lobed Hailstones

et al. 2020

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The complex surface geometries of hailstones affect their fall behavior, fall speeds, and growth. Systematic experimental investigations on the influence of the number and length of lobes on the fall velocity and the drag coefficient of hailstones were performed in the Mainz vertical wind tunnel to provide relationships for use in numerical models. For this purpose, 3D prints of four artificial lobed hailstone models as well as spheres were used. The derived drag coefficients show no dependency in the Reynolds number in the range between 25,000 and 85,000. Further, the drag coefficients were found to increase with increasing length of lobes. All lobed hailstones show higher or similar drag coefficients than spheres. The terminal velocities of the the hailstones with short lobes are very close to each other and only reduced by about 6% from those of a sphere. The terminal velocities from the long lobed hailstones deviate up to 21% from a sphere. The results indicate that lobes on the surface of hailstones reduce their kinetic energy by a factor of up to 3 compared to a sphere. This has important consequences for the estimation of the destructive potential of hailstones.

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Section: Hail Productionmentioning

confidence: 63%

Section: Hail Productionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A Wind Tunnel Investigation into the Aerodynamics of Lobed Hailstones

et al. 2020

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Numerical thermal–hydraulic analysis and multiobjective design optimization of a printed circuit heat exchanger with airfoil overlap fin channels

Kuo

Xie

Chueh

2023

Engineering Reports

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In this study, we numerically investigated the performance of a printed circuit heat exchanger (PCHE) featuring National Advisory Committee for Aeronautics (NACA) 0020 airfoil overlap fins integrated into its straight flow channels. Numerical simulations were performed by solving Navier–Stokes and energy equations to analyze liquid water at temperatures ranging from 30 to 90°C, which is possible for use with a geothermal heating system, for example. The optimization of the PCHE airfoil fin geometry is performed using nondominated sorting genetic algorithm II (NSGA‐II) with three design features: front, back, and overlap lengths. The effectiveness and pressure drop of the PCHE are evaluated as two objective functions. The present study shows that, when a Reynolds number falls between 1088 and 5000, the overlapping airfoils exhibit lower pressure drops and higher convective heat flux relative to the separate airfoils, and an increase in overlap length always decreases the pressure drop positively. It is also found that using overlapping airfoils of front length of 0.1 mm, back length of 0.119 mm, and overlap length of 0.203 mm leads to almost the same effectiveness and a 22% decrease in pressure drop (which is generally believed to preferably maintain the high heat transfer performance and minimize pressure drop, as a favorable design), compared to a base design of the airfoils with front and back lengths of 0.2 mm and an overlap length of 0.1 mm.

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Flow Fields and Fall Attitudes of Ice Hydrometeors

Wang

2020

Atmosphere, Earth, Ocean &Amp; Space

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A numerical study of flow fields of lobed hailstones falling in air

Cited by 10 publications

References 12 publications

A Wind Tunnel Investigation into the Aerodynamics of Lobed Hailstones

A Wind Tunnel Investigation into the Aerodynamics of Lobed Hailstones

Numerical thermal–hydraulic analysis and multiobjective design optimization of a printed circuit heat exchanger with airfoil overlap fin channels

Flow Fields and Fall Attitudes of Ice Hydrometeors

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