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In this article, the following conventions and definitions are to be understood: The Reynolds number Re is taken to be Re = V D / ν, where V is the mean velocity of fluid flow, D is the pipe diameter, and where ν is the kinematic viscosity μ / ρ, with μ the fluid's Dynamic viscosity, and ρ the fluid's density.
The number e is a mathematical constant approximately equal to 2.71828 that is the base of the natural logarithm and exponential function.It is sometimes called Euler's number, after the Swiss mathematician Leonhard Euler, though this can invite confusion with Euler numbers, or with Euler's constant, a different constant typically denoted .
When R ∗ > 100, the data asymptotically approach a horizontal line; they are independent of Re, f D, and ε / D . The intermediate range of 5 < R ∗ < 100 constitutes a transition from one behavior to the other. The data depart from the line B(R ∗) = R ∗ very slowly, reach a maximum near R ∗ = 10, then fall to a constant value.
In two dimensions, the Levi-Civita symbol is defined by: = {+ (,) = (,) (,) = (,) = The values can be arranged into a 2 × 2 antisymmetric matrix: = (). Use of the two-dimensional symbol is common in condensed matter, and in certain specialized high-energy topics like supersymmetry [1] and twistor theory, [2] where it appears in the context of 2-spinors.
To calculate the pressure drop in a given reactor, the following equation may be deduced: = + | |. This arrangement of the Ergun equation makes clear its close relationship to the simpler Kozeny-Carman equation, which describes laminar flow of fluids across packed beds via the first term on the right hand side.
The fixed points of the "epsilon mapping" form a normal function, whose fixed points form a normal function; this is known as the Veblen hierarchy (the Veblen functions with base φ 0 (α) = ω α). In the notation of the Veblen hierarchy, the epsilon mapping is φ 1 , and its fixed points are enumerated by φ 2 .
In both the original and the preconditioned conjugate gradient methods one only needs to set := in order to make them locally optimal, using the line search, steepest descent methods. With this substitution, vectors p are always the same as vectors z , so there is no need to store vectors p .
A radial function is a function : [,).When paired with a norm on a vector space ‖ ‖: [,), a function of the form = (‖ ‖) is said to be a radial kernel centered at .A radial function and the associated radial kernels are said to be radial basis functions if, for any finite set of nodes {} =, all of the following conditions are true: