Measurements of wind suppression effects of windbreak net using a wind tunnel for the purpose of applying numerical simulations

Abstract

Windbreak nets are most often used to prevent agricultural wind damage, since they are cheap and easy to install. However, little is provided concerning the dynamical characteristics of such windbreak nets, hampering the design of windbreak planning through the quantitative use of the latter. We measured both dynamical characteristics and wind fields around popular five windbreak materials using a wind tunnel. Subsequently, we tried to simulate the measured wind field using a numerical atmospheric model. The measured wind fields show various flow patterns around windbreaks well known in literature, with recirculating eddies for two spunbonded fabric windbreaks. The relationship between the wind field patterns and porosities of the windbreaks is more or less the same as in past studies, while the numerical simulations reproduce wind fields around the three popular windbreak nets fairly well. It is confirmed that the wind tunnel measurements and numerical simulations are reliable means to reproduce realistic wind field around popular windbreak nets.

Wind tunnel and field assessment of pollen dispersal in Soybean [Glycine max (L.) Merr.]

“…A wind tunnel (2.4W 9 2H 9 21L m, Fig. 1) from the Hazama Technical Research Institute in Tsukuba Ibaraki, Japan was used for the experiments (Takakura et al 1993;Ushiyama et al 2009). A constant airflow of 2 m s -1 was regulated using an ultrasonic anemometer, located at 12.5 m from the plant.…”

Three-dimensional prediction of maize pollen dispersal and cross-pollination, and the effects of windbreaks

“…This is the first study of numerical prediction of pollen dispersal and cross-pollination in which the effect of a windbreak net was incorporated. The drag force of the net was measured in a wind tunnel (Ushiyama et al, 2009) and appropriately incorporated into the model. As a result, the wind speeds close to the net on the downstream side agreed well with observations at the wind-nudging height.…”

“…The canopy model was also used to express the drag force of the windbreak net. For this purpose, C d and a L (z)+a s (z) were set uniformly at all heights to 1.02 and 10.0 m −1 , respectively, which were obtained from wind tunnel measurements (Ushiyama et al, 2009). In the case of the 2-mm-mesh net in the additional numerical experiment, C d and a L (z) + a s (z) were set uniformly to 0.57 and 1.0 m −1 , respectively (Ushiyama et al, 2009).…”