4.2 STEADY-STATE HEAT TRANSFER WITH END EFFECTS This first example illustrates the application of the ◦(1) scaling analysis procedure to a steady-state conductive heat-transfer problem for which an exact analytical solution is available. If the describing equations can be solved analytically, there is no need to apply scaling analysis to explore how the problem can be simplified. However, this problem is instructive in that the solution to the simplified equations obtained via scaling can be compared with the analytical solution to the unsimplified describing equations to assess the error incurred as a function of the magnitude of the dimensionless group, which needs to be small to justify the approximation. It will also illustrate region-of-influence scaling whereby we seek to determine the thickness of a region wherein some important effect is concentrated. Regionof-influence scaling is particularly important since it forms the basis of thermal boundary-layer theory and penetration theory.