ARCHER2 Calendar February 2024

Unsteady Flow Over Random Urban-like Obstacles: A Large Eddy Simulation using uDALES 2.0 Codebase

Dr Dipanjan Majumdar, Imperial College London, Civil and Environmental Engineering Department

uDALES stands as an open-source large-eddy simulation framework, specifically designed to tackle unsteady flows within the built environment. It is capable of simulating airflow, sensible and latent heat transfer, and pollutant dispersion within the urban atmospheric boundary layer. The simulation framework adopts the immersed boundary method to resolve buildings, supplemented with wall functions to account for surface shear stresses and heat fluxes. Additionally, a three-dimensional surface energy balance model establishes a two-way coupling, accommodating both man-made and vegetative materials. To achieve optimal performance, uDALES utilizes two dimensional domain decomposition, facilitating parallelization and resource utilization on supercomputers like ARCHER2 for exascale computing. The presented figure was generated while validating the latest version uDALES 2.0 against a classical study by Xie et al. (2008) on flow over random urban-like obstacles. It showcases the instantaneous stream-wise velocity contour at a spanwise plane intersecting the tallest building within the simulated domain.

This image was published on the February page of the ARCHER2 2024 printed calendar.