To work with OpenFoam, you should do these steps (as from my little experience)

1. Identify a suitable base solver (already encoded within suitable OF version) which satisfies your need/problem

2. Based on your test case, you have to choose suitable Boundary conditions which can work well with your solver

3. After you have got step 1 and step 2, just try to incorporate suitable turbulence model (usually now we have LES/RAS/K-epsilon models in OF version)

Now, based on your problem, you have have specified it as a constant density flow. Are you taking into account of buoyant effects for analysis? 

In order to correctly resolve the physics involved, you also will have to take care of a suitable mesh. Prepare it with respect to a feasible y+ and a reasonable resolution in the regions of mixing of the jet. For a axisymmetric jet, I assume that a 2D axisymmetric mesh is sufficient. This will reduce the computational time and resources. 

Also think of what physics to incorporate, i.e. compressible/incompressible, and choose an appropriate solver (refer to the OF manual)... Same for BC's. For Turbulence Model, I assume, that standard k-epsilon will do a good job at first, but this could be further improved or investigated starting from a reasonable initial simulation.

Article Computation of an Axisymmetric Jet using OpenFOAM