The wall-jet owing to plane jet imping and reattachment

The interaction of turbulence between a jet-like main flow under the wall-jet exist undoubtly, but the influence of the main flow to boundary-layer will be vanished rapidly in the vicinity of the wall. In this point of view, auther derived the velocity low in boundary-layer under the wall-jet, with a method that the boundary-layer devide into the wall region which consist the viscous sub-layer and the turbulent sub-layer, and outer-layer in where the influence of main flow exist. When the turbulence of the main flow not exist, the derived velocity low agree with Nikuradse's experimental results. If we have knowledge of the character about the main flow, it is possible to evaluate the growth of boundary-layer under the influence of turbulent main flow. From measurement of velocity distribution, it make evident that the main flow along wall after impinged or reattached to fixed boundary is devide accelated, uniform and decreased velocity region. A border or each region was determined experimentary, on the case of jet impingment, it was provided with a distance from an issumed section of jet to impinged point, and on the case of jet reattachment, it was provided with a flow scale and angle of reattached. Under the main flow model as mentioned above, the boundary layer growth was calculated by a little defferent method on the each case. The calculated results of the boundary layer growth are good agreement with experimental result on both case. From this agreement, we confirm that the presented velocity low will be help to make clear the mechanism of scour and criterion for scour downstream of a culvert and an outlet.