Fluid Flow

Abstract

Publisher Summary This chapter discusses the different types of fluid flow. Flow is defined as the quantity of a fluid. In laminar flow, a fluid moves in a steady manner, and there are no eddies or turbulences. This is the type of flow normally present in smooth tubes at low rates of flow. The flow is greatest in the center, being about twice the mean flow. As the side of the tube is approached, the flow becomes slower until it approaches zero at the wall. To drive a fluid through a tube, a pressure difference must be present across the ends. The ratio of pressure to flow is a constant known as the resistance R of the apparatus or tube concerned. A laminar flow may change to turbulent flow if a constriction is reached which results in an increase in the fluid velocity. In turbulent flow, the fluid no longer flows in a smooth fashion but swirls in eddy. The variation of fluid velocity across the tube is different in the turbulent flow from one which occurs in the laminar flow. The theoretical analysis of turbulent flow is highly complex although it is possible to predict some aspects of flow behavior. For turbulent flow in tubes that are rough on the inside, it is found that the flow is approximately proportional to the square root of the pressure.