The influence of radial entrance width of the circular cavity on incident shock wave focusing

Despite the achievement of shock wave focusing with certain reflectors,the influence of the radial entrance width of a circular cavity on the flow field has yet to be addressed.In this study,we systematically investigated the effects of the shock wave focusing process in a cavity based on the radial entrance widths.An experimental system was installed to research the evolution of the flow field under conditions with different radial entrance widths of 3.0,11.1,19.5,and 33.0 mm.A schlieren system was used to photograph the structures of the flow field in the cavity,and a data acquisition system was used to record the dynamic pressure histories of different points.A numerical simulation was carried out to investigate greater details of the shock wave focusing process.A third-order strong stability-preserving Runge-Kutta method,third-order weighed essential non-oscillation scheme,and an adaptive mesh refinement algorithm were adopted to simulate the shock wave reflection,diffraction,and focus process.Good agreement between the experimental and numerical results was observed.By comparing the evolution process of the flow field under the conditions of four different entrance cavity widths,we found that when the entrance width was 19.5 mm,there was the stronger intensity of the shock wave focusing in the focal region,and the larger pressure value at the apex of the cavity than the other three entrance widths,occur.This study improves our understanding of shock wave focusing.

Burrow Characteristics and Microhabitat Use of the Turpan Wonder Gecko Teratoscincus roborowskii (Squamata, Gekkonidae)

Burrow structural charactersitcs and microhabitat use of the Turpan wonder gecko Teratoscincus roborowskii （Gekkonidae） were studied between April and September of 2013 in the Turpan Eremophytes Botanic Garden, in the Turpan Depression of Western China. Burrow depth, entrance orientation, entrance height and width were observed. We assessed microhabitat selection and noted differences in microhabitat use among males, females, and juveniles. The magnitude of selection was measured using Jacobs＇ index of selectivity. Entrance height and width of the burrows of adults were significantly larger than those of juveniles, but the difference in burrow depth was not significant. The directional orientation of the burrow entrance showed a preference for the north-northeast and south-southeast, which were likely influenced by local prevailing winds and sunlight. Both the adult and juvenile geckos prefer to construct their burrows in sandy soil within a layer of loose soil whose thickness is greater than 30 cm. A majority of the burrows were located within 20 m of the nearest plant. Nearly half （48%） of the entrances of juveniles were located within 5 m of the nearest vegetation, significantly different from those of the adults. Results showed that the Turpan wonder gecko did not utilize microhabitats according to their availability, but rather that it preferred rnicrohabitats which contained dead wood or the caper bush. Our results suggested that burrow characteristics and microhabitat selection were important factors in T. roborowskii adaptation to harsh and arid desert habitats.