A rapid RANS solver for wind field simulations in urban environments

CAMIRA (Coupled Algorithm for Multigrid Immersed Boundary RANS) is a highly efficient solver for the incompressible RANS equations, designed for rapid wind field prediction in complex urban environments. It is based on a newly developed matrix free coupled scheme on a collocated finite volume grid, accelerated by FAS multigrid. Complex geometries are handled using a directional, mass conservative immersed boundary method. Prioritizing rapid turnaround times, CAMIRA uses simple zero-equation turbulence closures. This combination of methodologies leads to a solver that is simple to implement and very computationally efficient. CAMIRA has been validated against experimental data and benchmarked against established solvers, including those in ANSYS Fluent and OpenFOAM. Results demonstrate better than order-of-magnitude speedup against these solvers and linear scaling with problem size. The current implementation supports shared-memory parallelism.