You are asked to evaluate assorted fluid flows for their suitability in a given laboratory application. The following three flow choices, expressed in terms of the two-dimensional velocity fields in the xy-plane, are made available. P. u = 2y, v = - 3x Q. u = 3xy, v = 0 R. u = 2x, v = 2y Which flow(s) should be recommended when the application requires the flow to be incompressible and irrotational?