Consider fully developed laminar flow with constant properties in a circular tube. Let the surface be insulated, but let there be heat generation within the fluid at a rate S, W/m3, that is everywhere the same. From an examination of the applicable energy differential equation alone, deduce the approximate shape of the temperature profile within the fluid, and determine whether the highest temperature of the fluid at any axial position occurs at the tube wall or at the tube centerline. Explain the reasons for the result.