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In engineering, the Moody chart or Moody diagram (also Stanton diagram) is a graph in non-dimensional form that relates the Darcy–Weisbach friction factor f D, Reynolds number Re, and surface roughness for fully developed flow in a circular pipe. It can be used to predict pressure drop or flow rate down such a pipe.
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 pipe's relative roughness ε / D, where ε is the pipe's effective roughness height and D the pipe ...
Rugosity calculations are commonly used in materials science to characterize surfaces, amongst others, in marine science to characterize seafloor habitats. A common technique to measure seafloor rugosity is Risk's chain-and-tape method [2] but with the advent of underwater photography less invasive quantitative methods have been developed.
where the roughness height ε is scaled to the pipe diameter D. Figure 3. Roughness function B vs. friction Reynolds number R ∗. The data fall on a single trajectory when plotted in this way. The regime R ∗ < 1 is effectively that of smooth pipe flow. For large R ∗, the roughness function B approaches a constant value.
Hydraulic roughness is the measure of the amount of frictional resistance water experiences when passing over land and channel features. [1] It quantifies the impact of surface irregularities and obstructions on the flow of water. One roughness coefficient is Manning's n-value. [2]
Dimensionless numbers (or characteristic numbers) have an important role in analyzing the behavior of fluids and their flow as well as in other transport phenomena. [1] They include the Reynolds and the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, and flow speed.
The Hardy Cross method assumes that the flow going in and out of the system is known and that the pipe length, diameter, roughness and other key characteristics are also known or can be assumed. [1] The method also assumes that the relation between flow rate and head loss is known, but the method does not require any particular relation to be used.
The basic GD&T symbol for surface roughness. Surface roughness or simply roughness is the quality of a surface of not being smooth and it is hence linked to human perception of the surface texture. From a mathematical perspective it is related to the spatial variability structure of surfaces, and inherently it is a multiscale property.