a) Define incompressible flow and incompressible fluid. Must the flow of a compressible fluid necessarily be treated as compressible? b) What is forced convection? How does it differ from natural convection? Is convection caused by winds forced or natural convection? c) What is external forced convection? How does it differ from internal forced convection? Can a heat transfer system involve both internal and external convection at the same time? Give an example. d) What is the physical significance of the Nusselt number? How is it defined? e) When is heat transfer through a fluid conduction and when is it convection? For what case is rate of heat transfer higher? How does the convection heat transfer coefficient differ from t thermal conductivity of a fluid? f) What is the no-slip condition? What causes it? g) What is Newtonian fluid? Is water a Newtonian fluid?