  We use the weakly nonlocal hydrodynamics approach to obtain a dynamical
equation for the peculiar velocity field in which the viscosity term is
physically motivated. Based on some properties of the Ginzburg-Landau equation
and the wave mechanics analog of hydrodynamics we find the nonlocal adhesion
approximation taking into account the internal structures of the Zeldovich
pancakes. If the internal structures correspond to significant mesoscopic
fluctuations, viscosity is probably driven by a stochastic force and dynamics
is given by the noisy Burgers equation.
