Numerical simulation of particulate matter transport in the atmospheric urban boundary layer using Lagrangian approach: physical problems and parallel implementation

This paper presents the results of the development of a numerical model of the Lagrangian particle transport and the application of parallel computation methods to increase the efficiency of the software implementation of the model. The model is a software package allowing calculations of transport and deposition of aerosol particles taking into account the properties of particles and input data describing atmospheric conditions and the underlying surface geometry. The dynamic core, physical parameterizations, numerical implementation, and algorithm of the model are described. Initially, the model has been used for computationally low-intensive problems. In this paper, given the need to use the model in computationally intensive problems, we conduct optimization of the sequential software implementation of the model, as well as creation of software implementations of the model with the use of parallel computing technologies OpenMP, MPI, CUDA. The results of testing of different implementations of the model show that optimization of the most computationally complex blocks in the sequential version of the model can reduce the execution time by 27%, at the same time the use of parallel computing technologies allows to achieve acceleration by several orders of magnitude. The use of OpenMP in dynamic block of the model resulted in acceleration of block up to 4 times, the use of MPI – up to 8 times, the use of CUDA – up to 16 times, all other conditions being equal. Recommendations on the choice of parallel computing technology depending on the properties of the computing system are proposed.