Fundamentals of Fluid Turbulence
We give a brief account of the derivation of fundamental equations [3.1, 3.2]. We take a fluid volume V with its surface denoted by S, as in figure 3.1 ( n is the outward unit vector normal to S). For arbitrary V, we consider the temporal change of ∫ V η d V , where η represents a set of quantities per unit mass. The temporal change arises from the two effects as () ∂ ∂ t ∫ V η d V = ∫ S η ( − u n ) d S + S η . Fluid volume for conservation laws.