## 1 Introduction  
Wind loads are the most critical environmental forces acting on building structures, particularly in a typhoon-prone area. The reference wind pressure associated with extreme wind events is the important parameter to determine the design wind load. In coastal and mountainous areas of Southeast China, the wind pressure is not only affected by typhoons, but also by the topography of mountains and valleys. Due to social economic development reasons, only a few meteorological stations have been deployed in those mountainous regions. It is difficult to determine the reference wind pressure for the design of building and bridge structures there. Although wind tunnel tests are effective to study wind effects, the size of the wind tunnel is limited to model a large area with natural terrain. CFD (computational fluid dynamics) has become an alternative numerical approach to carry out flow or wind simulations over a given computational domain. The CFD technique has been widely used in many research fields. In the design of a centrifugal compressor, [PERSON] et al. identified the differences in the performance of the centrifugal compressor with a ported shroud and compared them to the baseline case by a CFD simulation campaign using a simplified model [1]. In wind engineering fields, the CFD technique is mainly applied to simulate wind flow over an area and the wind effects on structures. To predict the wind flow, various \(k\)-\(\varepsilon\) and \(k\)-\(\omega\) turbulence models have been commonly used [2; 3; 4]. [PERSON] et al. compared the mean wind speed, turbulent kinetic energy, and turbulence dissipation rate profiles from the wind tunnel measurements and CFD simulations at 25 positions and discussed the deviations between the experimental and numerical results [5]. Various meshing and visualizing methods have also been developed to improve the efficiency and accuracy of the CFD simulation by some researchers [6; 7; 8; 9]. Some studies have focused on determining the appropriate size of the computational domain, which affects the blocking rate and in turn the computational accuracy [10; 11; 12].  
The CFD simulation method also provides an important tool for wind field research over a large area. [PERSON] et al. coupled the WRF (weather research and forecast) model with a CFD model, and conducted a sensitivity analysis to evaluate which scheme provided the best boundary conditions for CFD [13]. [PERSON] et al. carried out an urban wind field simulation under Typhoon Chan-hom based on WRF modeling and LES (large Eddy simulation) by CFD [14]. Urban-scale wind flow simulation has also been implemented by integrating CFD and the GIS (geographic information system) technique [15; 16; 17; 18]. In the wind energy industry, great progress has been made in the research of wind farm site selection and wind resource assessment by CFD [19; 20; 21; 22; 23; 24]. The mesoscale WRF mode based on the non-static-equilibrium Eulerian equation model was introduced for the high temporal-spatial resolution simulation of typhoon effects [25]. CFD simulations were also used for the wind environment assessment of individual buildings or clusters of buildings [26].  
To sum up, the current CFD simulation of the wind environment mainly focuses on a relatively small computational domain covering several building blocks or building clusters. There are few wind field simulation studies for a region stretching over 100 km in a mesoscale. The optimization of the mesh scheme and the selection of turbulence models need to be further explored in the meso-scale CFD simulations. Specifically, a novel approach for the mesoscale CFD simulation of the wind field is proposed, and the simulation results are further used to determine the reference wind pressure for the structural design of buildings in a coastal and mountainous region.