CFD simulations of turbulent buoyant atmospheric flows over complex geometry: Solver development in OpenFOAM

• We develop a CFD OpenFoam solver to simulate air circulation inside open pit mines.
• We test the solver against several experimental and numerical data.
• DES allows the simulation of developed turbulence around complex geometry.
• Buoyancy and stratification are solved including density as a variable in equations.
• We report the ability of the model to solve convective cases.

This paper, first of a two-part work, presents an overview of the development of a computational fluid dynamics (CFD) solver in OpenFOAM platform to simulate the internal ventilation regime within an open pit including the effects of developed turbulence, buoyancy and stratification. To incorporate the effect of stratification in the simulations we have chosen a formulation that includes density as a variable in the system of equations, thus facilitating further study of buoyant flows. Given the importance of turbulence in this type of large-scale flows we have used Large Eddy Simulation (LES) to incorporate it in the calculation, using a Detached Eddy Simulation (DES) approach to solve the flow near walls. Specific initial and boundary conditions were defined.The results presented in this paper, including several tests of the solver where we compared our results with experimental or numerical data, have demonstrated the validity of using OpenFOAM to study this type of complex multiphysics problems. Especially advantageous in this regard are the flexibility provided by the modular structure of the code, the possibility of defining specific boundary and initial conditions for each case, and the ability of generating detailed meshes of complex geometries. Also we probed the benefits of using a DES approach, allowing us to solve developed turbulence and the interaction of the flow with detailed geometry. A second paper associated to this work will expose the application of the solver to large open pit mines, simulating the particular case of Chuquicamata, one of the largest open pit mines in the world, located in northern Chile.