Three-dimensional numerical simulation of an equilateral triangular turbulent free jet

Purpose - This paper aims to describe the numerical simulation of a three-dimensional turbulent free jet issuing from a sharp-edged equilateral triangular orifice into still air. Design/Methodology/approach - The numerical simulation was carried out by solving the governing three-dimensional Reynolds-averaged Navier-Stokes equations. Several two-equation eddy-viscosity models (i.e. the standard k-epsilon, renormalization group (RNG) k-epsilon, realizable k-epsilon, shear-stress transport (SST) k-omega), as well as the Reynolds stress models (i.e. the standard RSM and the SSG) were tested to simulate the flowfield. The numerical predictions were compared with experimental data in order to assess the capability and limitations of the various turbulent models examined in this work. Findings - The vena contracta effect was predicted by all the tested models. Among the eddy-viscosity models only the realizable k-epsilon model showed good agreement of the near-field jet decay. None of the eddy-viscosity models was capable of predicting the profiles of the jet turbulence intensities. The RSMs, especially the standard RSM, were able to produce much better predictions of the features of the jet in comparison with the eddy-viscosity models. The standard RSM predictions were found to agree reasonably well with the experimental data. Research limitations/implications - The conclusion, that among the tested RANS turbulence closure models, the RSM appeared the only one capable of reproducing reasonably well the experimental data concerns only the jet flow case examined here. Also, the average computational time for a single run was quite long, i.e. 340 h, but it is believed that parallel computing will reduce it considerably. Originality/value - The numerical results reported in this paper provide a comparison between several RANS turbulence closure models for simulating a turbulent free jet issuing from an equilateral triangular nozzle.