Comparison of turbulence models in simulating jet flow from a cross-shaped orifice

A Computational Fluid Dynamics investigation of a free lobed jet was conducted at moderate Reynolds number. The aimed application is related to the optimization of air diffuser for heating, ventilation and air conditioning systems. Experimental data of an orifice cross-shaped jet (El-Hassan et al. 2011) are used to evaluate seven turbulence models in the prediction of such a flow. The study is motivated by the observed changes in the prediction of local and global mean-flow quantities as a function of the considered turbulence model and by the lack of consensus in the literature on their performance to predict jet flows with significant three-dimensionality. The study reveals that none of the turbulence models is able to predict well all jet characteristics in the same time. Reynolds stress turbulence model leads to a better agreement between the numerical results and the experimental data for the local jet flow expansion, whereas global flow expansion and ambient air induction are better predicted by the shear stress transport k-ω turbulence model. All linear (Low Reynolds and Renormalization Group) and nonlinear (quadratic and cubic) k-ε turbulence models overestimate local and global expansions and ambient air induction. The k-ω turbulence model underestimates on one hand the global expansion and the ambient air induction and on the other hand the transverse jet deformation is not well predicted. The turbulence kinetic energy increases unrealistically in the jet near field for all k-ε turbulence models and RSM. In this region the SST k-ω model was in close agreement with measurements.