Fluid Mechanics for Chemical Engineers: with Microfluidics, CFD, and COMSOL Multiphysics 5

Chapter 7. Laplace’s Equation, Irrotational and Porous-Media Flows

7.1 Introduction

THE previous chapter dealt with fluid motions in which the viscosity always played a key role. However, away from a solid boundary, the effect of viscosity is frequently small and may be neglected. The example was given at the end of Section 5.2 of the rotation of a cup containing coffee, in which there was little perceptible rotation of the liquid itself. For a cup of molasses, the situation would obviously be different.

There are several practical situations in which the fluid can be treated as essentially inviscid, occurring for example in the flow of air relative to an airplane, flow of water in lakes and harbors, surface waves on water, air motion in tornadoes, ...