  We present an analytical model for the time-developing turbulent boundary
layer (TD-TBL) over a flat plate. The model provides explicit formulae for the
temporal behavior of the wall-shear stress and both the temporal and spatial
distributions of the mean streamwise velocity, the turbulence kinetic energy
and Reynolds shear stress. The resulting profiles are in good agreement with
the DNS results of spatially-developing turbulent boundary layers at momentum
thickness Reynolds number equal to 1430 and 2900. Our analytical model is, to
the best of our knowledge, the first of its kind for TD-TBL.
