Wall modeled immersed boundary method for high Reynolds number flow over complex terrain

TL;DR

This paper introduces a simplified, more efficient wall modeled immersed boundary method for simulating high Reynolds number flows over complex terrain, validated against wind tunnel data, enabling higher resolution simulations on supercomputers.

Contribution

A simplified version of the immersed boundary method that is easier to implement and more computationally efficient for high Reynolds number flows over complex terrain.

Findings

Good agreement with wind tunnel measurements

Method suitable for high Reynolds number flow modeling

Enables higher grid resolutions on supercomputers

Abstract

Modeling the effect of complex terrain on high Reynolds number flows is important to improve our understanding of flow dynamics in wind farms and the dispersion of pollen and pollutants in hilly or mountainous terrain as well as the flow in urban areas. Unfortunately, simulating high Reynolds number flows over complex terrain is still a big challenge. Therefore, we present a simplified version of the wall modeled immersed boundary method by Chester et al. (J. Comput. Phys. 2007; 225: 427-448). By preventing the extrapolation and iteration steps in the original method, the proposed approach is much easier to implement and more computationally efficient. Furthermore, the proposed method only requires information that is available to each processor and thus is much more efficient for simulations performed on a large number of cores. These are crucial considerations for algorithms that are deployed on modern supercomputers and will allow much higher grid resolutions to be considered. We validate our method against wind tunnel measurements for turbulent flows over wall-mounted cubes, a two dimensional ridge, and a three-dimensional hill. We find very good agreement between the simulation results and the measurement data, which shows this method is suitable to model high Reynolds number flows over complex terrain.