This thesis reports on a numerical study of a round, isothermal turbulent jet of incompressible fluid, impinging normally on a flat wall at a different temperature. The main body of the thesis deals with LES studies using the dynamic subgrid-scale model, of flow and heat transfer in a round impinging jet at Re=20000 and orifice-to-plate distance h/D=2. The LES were performed using the in-house unstructured finite-volume computational code T-FlowS.The second focus of the thesis was the study of the feasibility of combining the LES and RANS approaches into a hybrid method. The goal was to...