Large Eddy Simulation of the flow past a square cylinder

Turbulence is a phenomenon that occurs frequently in nature and that is also a situation present in almost all industrial applications. In this work, the simulation of turbulent vortex shedding from a bluff-body square cylinder has been undertaken using Large Eddy Simulation technique (LES). The objective of this work was to implement this type of simulations in parallel PHOENICS and validate the results in order to apply them to practical cases like bluff-body jet burners. The LES Smagorinsky model and auxiliary calculations like Adam-Moulton high order time scheme have been implemented as FORTRAN subroutines into the code. The turbulent flow has a Reynolds number of 21400 and it corresponds to a flow of water over a square cylinder. This has been previously used by several authors to validate turbulence CFD models. The influences of the LES model and numerical schemes are analyzed and the most important flow parameters are calculated. The results agree with experimental and numerical available data. Also, a comparison between using LES and Reynolds Averaged Navier-Stokes Equations with the k − model have been made and some differences are pointed out. The results allow to conclude that the LES model improves the accuracy of the the k− model and reproduces adequately the flow motion and the vortex shedding. The simulation has been performed in parallel mode on a varying number of nodes of a 66-processor cluster. The parallel calculation results in significant time savings compared with the sequential (single-processor) run. The next step will be to apply this model to a bluff-body flame in order to study the interaction between turbulence and chemistry in industrial burners.