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Numerical evaluation of the scale problem on the wind flow of a windbreak.

Liu B, Qu J, Zhang W, Tan L, Gao Y - Sci Rep (2014)

Bottom Line: In this study, we perform a numerical comparison between a scaled wind-fence experimental model and an actual-sized fence via computational fluid dynamics simulations.The results show that although the general field pattern can be captured in a reduced-scale wind tunnel or numerical model, several flow characteristics near obstacles are not proportional to the size of the model and thus cannot be extrapolated directly.For example, the small vortex behind a low-porosity fence with a scale of 1:50 is approximately 4 times larger than that behind a full-scale fence.

View Article: PubMed Central - PubMed

Affiliation: Dunhuang Gobi Desert Ecological and Engineering Research Station, Key Laboratory of Desert and Desertification, Chinese Academy of Sciences, Lanzhou 730000, China.

ABSTRACT
The airflow field around wind fences with different porosities, which are important in determining the efficiency of fences as a windbreak, is typically studied via scaled wind tunnel experiments and numerical simulations. However, the scale problem in wind tunnels or numerical models is rarely researched. In this study, we perform a numerical comparison between a scaled wind-fence experimental model and an actual-sized fence via computational fluid dynamics simulations. The results show that although the general field pattern can be captured in a reduced-scale wind tunnel or numerical model, several flow characteristics near obstacles are not proportional to the size of the model and thus cannot be extrapolated directly. For example, the small vortex behind a low-porosity fence with a scale of 1:50 is approximately 4 times larger than that behind a full-scale fence.

No MeSH data available.


Related in: MedlinePlus

Comparison between the flow contours behind a fence at two scales, where η = 0.3 and v = 10 m/s.
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f4: Comparison between the flow contours behind a fence at two scales, where η = 0.3 and v = 10 m/s.

Mentions: A direct comparison between the flow fields behind the two scaled fences revised several general similarities and differences caused by the scale effect. The lift streamline that appoached the fence, the flow compression above the fence, the bleed flow immediately after the fence, the high-velocity region above the fence, the flow reattachment distance and the shape of the separation cell for the two scale simulations are consistent, as shown in Fig. 4 for a porosity of 0.3 and an inlet wind speed of 10 m/s.


Numerical evaluation of the scale problem on the wind flow of a windbreak.

Liu B, Qu J, Zhang W, Tan L, Gao Y - Sci Rep (2014)

Comparison between the flow contours behind a fence at two scales, where η = 0.3 and v = 10 m/s.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4196098&req=5

f4: Comparison between the flow contours behind a fence at two scales, where η = 0.3 and v = 10 m/s.
Mentions: A direct comparison between the flow fields behind the two scaled fences revised several general similarities and differences caused by the scale effect. The lift streamline that appoached the fence, the flow compression above the fence, the bleed flow immediately after the fence, the high-velocity region above the fence, the flow reattachment distance and the shape of the separation cell for the two scale simulations are consistent, as shown in Fig. 4 for a porosity of 0.3 and an inlet wind speed of 10 m/s.

Bottom Line: In this study, we perform a numerical comparison between a scaled wind-fence experimental model and an actual-sized fence via computational fluid dynamics simulations.The results show that although the general field pattern can be captured in a reduced-scale wind tunnel or numerical model, several flow characteristics near obstacles are not proportional to the size of the model and thus cannot be extrapolated directly.For example, the small vortex behind a low-porosity fence with a scale of 1:50 is approximately 4 times larger than that behind a full-scale fence.

View Article: PubMed Central - PubMed

Affiliation: Dunhuang Gobi Desert Ecological and Engineering Research Station, Key Laboratory of Desert and Desertification, Chinese Academy of Sciences, Lanzhou 730000, China.

ABSTRACT
The airflow field around wind fences with different porosities, which are important in determining the efficiency of fences as a windbreak, is typically studied via scaled wind tunnel experiments and numerical simulations. However, the scale problem in wind tunnels or numerical models is rarely researched. In this study, we perform a numerical comparison between a scaled wind-fence experimental model and an actual-sized fence via computational fluid dynamics simulations. The results show that although the general field pattern can be captured in a reduced-scale wind tunnel or numerical model, several flow characteristics near obstacles are not proportional to the size of the model and thus cannot be extrapolated directly. For example, the small vortex behind a low-porosity fence with a scale of 1:50 is approximately 4 times larger than that behind a full-scale fence.

No MeSH data available.


Related in: MedlinePlus