A variational multiscale framework for atmospheric turbulent flows over complex environmental terrains

A residual-based variational multi-scale (VMS) modeling framework is applied to simulate atmospheric flow over complex environmental terrains. The VMS framework is verified and validated using two test cases using linear finite element (FEM) and quadratic non-uniform rational B-spline (NURBS) discretizations. First, the flow over the 3D, axisymmetric Gaussian hill (normally distributed surface) is used to compare the results with FEM and NURBS discretization. Next, the actual terrain of the Bolund hill is used to demonstrate the efficacy of the framework. Good agreement with published data, coming from simulations and field measurements, is achieved, with the NURBS discretization showing much better per-degree-of-freedom accuracy compared with linear FEM. The paper includes a comprehensive review of experimental and numerical methods, and the corresponding challenges, for complex-terrain flows, which provides a proper context for the developments presented in this work. •VMS framework is applied to simulate atmospheric flow over complex environmental terrains.•FEM and NURBS discretization techniques are adopted to simulate the flow over the Gaussian hill, and Bolund hill is modeled using NURBS-based discretization.•Mesh refinement study is performed to ensure the grid converged solution is obtained.•Good agreement with field measurements is achieved at various locations.