  The evolution with Reynolds number of the dissipation function, normalized by
wall variables, is investigated using direct numerical simulation (DNS)
databases for incompressible turbulent Poiseuille flow in a plane channel, at
friction Reynolds numbers up to Re\tau = 2000. DNS results show that the mean
part, directly dissipated by the mean flow, reaches a constant value while the
turbulent part, converted into turbulent kinetic energy before being
dissipated, follows a logarithmic law. This result shows that the logarithmic
law of friction can be obtained without any assumption on the mean velocity
distribution. The proposed law is in good agreement with experimental results
in plane-channel and boundary layer flows.
