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The spatial characteristics of wind-sand flow development are important for the morphological analysis of sand dunes (especially barchan dunes) used for curbing desertification projects. However, in previous studies, results were mostly obtained under the premise of a stable wind field. In this study, natural unsteady wind is accounted for, and the two-dimensional turbulent flow equilibrium differential equation (the N–S equation) is solved by large-eddy simulation method. On the premise that the characteristics of the simulated flow field are consistent with those of natural wind field, a point force model is used to calculate the trajectory of a large number of dust particles. The analysis focuses on the correlation between the development distance of the wind-sand flow, the turbulence characteristics of the wind field, and the particle size of sand. The results show that the saturation length of the unsteady incoming flow is generally shorter than that of the steady incoming flow (The turbulence intensity is equal to 0). Moreover, the overshoot phenomenon is not obvious when the particle size is small, the maximum value of the sand transport rate is generally smaller than that in stable inflow environment, and the position is more forward as the particle size increases. In addition, the saturation length decreases with an increase in turbulence intensity, and the turbulence intensity is different for the sand transport rate after space development is stable. The sand transport rate is not only delayed in time (

The near-ground turbulent flow of nature air should have an important influence on the wind-sand flow, because of the vegetation and/or micro-topography. However, due to the complexity of turbulent flows, the effects of such turbulences and dust particles are still unknown. In this paper, the large eddy simulation–discrete element method was used to simulate the wind-sand flow. The results show that the response time of the wind-sand flow to turbulence is approximately 1.6 s. In addition, the response time increases rapidly as the particle size increases. The turbulence impact on the sand transport rate first increases and then decreases as the wind velocity fluctuation intensity increases. The sand transport rate is enhanced when the turbulence intensity is less than 0.25, whereas it is weakened when the turbulence intensity exceeds 0.25. Furthermore, the smaller the particle size, the more significant the effect. The effect of turbulence is mainly concentrated at 0.1–0.2 m from the ground and the turbulence increases the height of the wind-sand flow.

In order to study turbulence conditions in an underwater square cavity, the large eddy simulation method was adopted to analyze flow field distributions in the cavity as well as its development and pressure pulsation characteristics at some key positions. MATLAB was also adopted to realize Fast Fourier Transform of signals in time domain and obtain pressure pulsation levels in frequency domain. Based on the analyzed results, pressure pulsation characteristics of key points in the cavity were further discussed. The results showed that pressure pulsation frequencies and characteristics were different with different positions in the square cavity and were closely related with relevant vortex motion states. It was found through comparisons with the experimental results, that pressure pulsation simulation had a good consistency with the experiment when the analyzed frequency was more than 31.5 Hz. As a result, feasibility and accuracy of numerical simulation and Fourier analysis methods were verified. Finally, a numerical model of square cavity in near sound field was built, and sound source intensity distributions at two frequency points were extracted. It could be found that the sound source intensity was large at the rear-edge step, which was consistent with the intensity distribution of vortices. Therefore, reliability of the numerical model in this paper was indirectly verified in the results.