 motion viscou liquid paraboloid motion viscou liquid paraboloid approxim solut steadi flow incompress viscou liquid paraboloid revolut describ assumpt form stoke stream function substitut navier-stoke equat paraboloid coordin make suitabl approxim non-linear differenti equat function deduc solut equat depend reynold number flow consid exampl numer integr illustr properti function reynold number vari 0 0001 approxim solut perfect fluid flow boundari allow displac call boundari layer 