The flow of a viscous incompressible fluid between two parallel plates due to the normal motion of
the plates is investigated. The unsteady Navier-Stokes equations are reduced to a nonlinear fourthorder
differential equation by using similarity solutions. Homotopy analysis method HAM is
used to solve this nonlinear equation analytically. The convergence of the obtained series solution
is carefully analyzed. The validity of our solutions is verified by the numerical results obtained by
fourth-order Runge-Kutta.
