Problem
Consider an incompressible flow in a periodic 2D domain of side 2t in each direction. Assume the initial conditions for velocity are of the form
u(x,y,t=0) = sin(x)cos(y), v(x,y,t=0) = -cos(x)sin(y).
(3)
Using these initial conditions and the Navier-Stokes equations, find the pressure and velocity at all times, assuming that u = u(x,y,t = 0)F(t) and v = v(x,y,t = 0)F(t) by finding F(t).