I am to find the velocity distribution where there is non steady flow of a Newtonian fluid in a circular pipe. I did a mass and momentum balance around the system and ended up with the following equation: dp/ds = 4 + 1/e*d/de(e*dp/de) The derivatives in the equation are partial derivatives the values of p,s,e are dimensionless numbers. I am to assume that the solution is separable and then use finite difference method to solve for p. This is where i am having problems. What will the equation be after the assumption is made and the equation is simplified. I have attempted the question: I equated the right hand side = 0: 4 + 1/e*d/de(e*dp/de) = 0 and made the partial derivatives total derivatives and then applied the chain rule: 4 + 1/e*dp/de + d/de(dp/de). Is this correct????????