8.1 Introduction
Integration is one of the common mathematical procedures used by engineers. Chemical engineers rely on integration when study chemical reaction, fluid dynamics, transport phenomena, unit operation, and chemical engineering thermodynamics.
While it is true that analytical integration is usually preferred than numerical integration since analytical integration also gives insight on the effects of several factors on the value of integral, numerical integration is sometimes required since the integral cannot be displayed in closed form. For example, if one would like to evaluate (the error function), one has no way but to use numerical integration. (In fact, he/she can use tables appeared in mathematical handbooks, but the tables were prepared by numerical integration)
Consequently, numerical integration is the focus of this chapter. First, the simple trapezoidal rule is derived from difference operator and discussed. Then, the more accurate Simpson 1/3 and Simpson 3/8 rules are discussed. The examples related to chemical engineering will be illustrated. Finally, the students will gain some experience on VBA for Excel by performing numerical integration using VBA.
Before entering into the discussion of each method, we first have to understand the concept of integration. Let us review what the meaning of ∫_a^b▒f(x)dx is.