The spatial relationships between dissipation and production rates and vortical structures in turbulent boundary and mixing layers.

Data bases of all three velocity components as well as six components of the velocity gradient tensor measured with multi-sensor hot-wire probes in a turbulent boundary layer and a two-stream turbulent mixing layer were analysed. The remaining three velocity gradients were determined using Taylor's hypothesis. With these data, the ``instantaneous'' production and dissipation rates, defined by $P = - {\partial \overline{U}_i}/{\partial x_j}(u_i u_j)$ and $D = -\nu \left( \left({\partial u_i}/{\partial x_j} \right)^2 + ({\partial u_i}/ {\partial x_j})({\partial u_j}/{\partial x_i}) \right)$, respectively, were determined. Cross-correlating the fluctuations of these two signals reveals significant levels of correlation and an asymmetric pattern that persists at several cross-stream locations for both flows. Furthermore, correlating both the dissipation and production rates with a vortex identifier, $\omega_{x-y} = [(\omega_x)^2 + (\omega_y)^2]^{\frac {1}{2}}$, also reveals consistent cross-stream patterns. The magnitude of these correlations and their persistent shapes across the flows suggest that regions of concentrated rates of dissipation are primarily located in the cores of quasi- streamwise vortices for both these types of turbulent shear flow, whereas regions of rates of production are more concentrated on the peripheries of the vortices .