Assessment of low-Reynolds number k-ε turbulence models against highly buoyant flows

The most outstanding factor identified may be the fact that MK introduced the Taylor microscale as the near-wall length scale and combined it with the integral length to result in a combined turbulence length scale, which is valid over the entire range of a turbulent boundary layer. The eddy viscosity formula with the incorporation of the turbulence length scale is naturally expected to provide a better representation of flows with strong buoyancy due to wall heating, especially in the near-wall region, where the buoyancy effect mainly occurs. As a result, MK-simulated highly buoyant flows showed excellent agreement with experimental data when applied with the property-dependent turbulent Prandtl number and shear-stress-dependent damping length. A comparison with DNS data of the turbulence data obtained from RANS calculations with MK also showed a good agreement.