Numerical Simulation Study of Spatial wind Fields in Grotto Areas Based on Oblique Photogrammetric Modeling

Abstract

Grotto sites are often located in complex terrain such as cliffs, terraces, or river valleys, where the wind field within these grotto areas is influenced by the complex topography. This study develops and evaluates a CFD-based workflow that integrates UAV oblique photogrammetry, three-dimensional terrain reconstruction, field measurements, and steady-state Reynolds-averaged Navier–Stokes (RANS) simulation to investigate the local wind field of the Xumishan Grottoes, China, under neutral atmospheric stratification. This research aims to achieve two objectives: (1) to construct a high-precision digital model of the complex terrain for the numerical simulation process using UAV technology; and (2) to conduct a numerical simulation study of the local-scale spatial wind field over complex terrain under neutral atmospheric stratification conditions, with the wind field within the Xumishan Grotto area as the research subject. The data show that the simulated wind speed ratio and wind direction obtained using the numerical method closely match the measured values, with an average relative error of less than 20%. These results indicate that the UAV-derived terrain-to-CFD workflow can reproduce the dominant spatial pattern of local wind exposure under the tested conditions and provide useful information for identifying wind-sensitive grotto areas, prioritising field monitoring, assessing potential wind-erosion risks, and supporting preventive conservation planning.