Apply Navier - Stokes equation to find an expression for velocity distribution for laminar flow of Newtonian fluid in thin film along an inclined flat plate. The equations of motion for Cartesian co - ordinate ( x , y , z ) are given below. ( d e l x d e l x + v x d e l x x d e l x + v y d e l v x d e l y + v z d e l v x d e l z ) = - d e l d e l x + [ d e l 2 v x d e l x 2 + d e l 2 v x d e l y 2 + d e l 2 v x d e l z 2 ] + D g x p ( d e l v y d e l + v x d e l v y d e l x + v y d e l v y d e l y + v z d e l v y d e l z ) = d e l p d e l y + [ d e l 2 v y d e l x 2 + d e l 2 v y d e l y 2 + d e l 2 v y d e l 2 ] + p g , ( d e l v z d e l + v x d e l v z d e l x + v y d e l v x d e l y + v z d e l v z d e l z ) = d e l p d e l z + [ d e l 2 v z d e l x 2 + d e l 2 v z d e l y 2 + d e l 2 v z z 2 ] + p g 3