ONE-EQUATION NEAR-WALL TURBULENCE MODELING WITH THE AID OF DIRECT SIMULATION DATA

The length scales appearing in the relations for the eddy viscosity an d dissipation rate in one-equation models were evaluated from direct n umerical (DNS) simulation data for developed channel and boundary-laye r flow at two Reynolds numbers each. To prepare the ground for the eva luation, the distribution of the most relevant mean-flow and turbulenc e quantities is presented and discussed, also with respect to Reynolds -number influence and to differences between channel and boundary-laye r flow. An alternative model is examined in which (v'2)1/2BAR is used as velocity scale instead of k1/2. With this velocity scale, the lengt h scales now appearing in the model follow closely a linear relationsh ip near the wall. The resulting length-scale relations together with a DNS based relation between v'2/kBAR and y = k1/2y/v form a new one-e quation model for use in near-wall regions. The new model was tested a s near wall component of a two-layer model by application to developed -channel, boundary-layer and backward-facing-step flows.