Structure Inclination Angle in a Turbulent Adverse Pressure Gradient Boundary Layer

The effect of a strong adverse pressure gradient on the turbulent structure in an equilibrium boundary layer was studied using two-point space-time correlations. The $ρuu$ correlations from the adverse pressure gradient layer were found to be inclined at a considerably higher angle with respect to the wall in the inner region than in the corresponding zero pressure gradient reference case. A wavelet analysis of the correlation data showed that differences in the inclination angle exist at all length scales larger than the boundary layer thickness. The inclination angle for the conventionally averaged correlation contours was found to be in close agreement with the inclinations derived from the wavelet filtered contours corresponding to the most energetic wave numbers.