Porosity/Distributed Resistance (PDR) Modelling in the CFD Solver PDRFOAM

The accidental release of hazardous gases might happen in various chemical plants, storage tanks, or in their transportation. The gas when released, interacts with the surrounding structures, i.e. vessels and pipelines, etc. It is also established that the objects of varying sizes do have an impact on the flow turbulence and combustion phenomena in gas explosions (Hjertager., Modelling, Identification and Control, 1985). The prediction of such explosions due to accidental leakage is usually modelled through computational fluid dynamics (CFD) approach. Porosity/distributed resistance (PDR), a pragmatic approach that takes into consideration the effects of numerous complicated geometries in a CFD solution, is a natural choice for this purpose. Sub-grid models for quantification of objects, that are smaller than the grids are formulated to integrate the under resolved nature of the simulations. In the current study, a PDR based CFD solver, PDRFOAM is used to explore non-reactive flows over pipe bundles of various configurations. We compared the modelled mean velocities and fluctuations with the experimental results to seek the efficacy of the solver. It is observed that the qualitative trends for the quantities are captured even for low mesh resolutions, which is in contrast to the standard body fitted mesh approach. Further, the solver is able to predict the maximum turbulent kinetic energy levels in the vicinity of the pipe/obstacle appreciably. The efficacy for the solver in congested environment is also explored for the cases where pipes are placed side-by-side to each other.