1. The problem statement, all variables and given/known data An experimentalist has measured the u-velocity component of a two-dimensional flow field. It is approximated by u = (1/3)( xy) (y^2) It is also known that the v-velocity is zero along the line y=0. 2. Relevant equations ∇V=du/dx+dv/dy (partial derivatives) 3. The attempt at a solution The solution is found by setting du/dx+dv/dy=0 (partial derivatives), solving the differential equation and then using the boundary conditions at v=0, y=0 to find the constant. How can we set the velocity gradient equal to zero? Why is it safe to assume that there is no velocity gradient?