There are many practical situations when jets are emanating from non-axis-symmetric apertures. The complexities associated to the numerical modelling of a high aspect ratio jet is embedded in its physical complexity. Consequently, the numerical modelling does not only require a high mesh resolution, but furthermore it requires a careful construction of the inlet boundary velocity. The present work consists of a series of Large Eddy Simulation (LES) simulations using different inflow boundary conditions. This work is aimed to find suitable inlet boundary conditions which resemble the turbulent features that can be expected near the jet orifice. The turbulent inlet conditions are constructed by means of a variable velocity. The velocity profile is constructed such that the statistical quantities for turbulence are satisfied, this includes a correct turbulent intensity of the velocity signal and an ‘a priori’ selected frequency spectrum. Experimental work of Quinn et al. (5) is used to validate the computational data.