On conditioned averages for intermittent turbulent flows

A conditioning function is generally used to discriminate between the turbulent and non-turbulent zones in intermittent flows. Any fluid-mechanical property is conditioned by multiplying it by the intermittency function. A formalism is developed in which some integrals of the fluid-mechanical variables at the interface are important ingredients with a precise physical meaning. The present ideas may prove to be useful in turbulence dynamics and turbulent mixing of scalars.