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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 pipe's relative roughness ε / D, where ε is the pipe's effective roughness height and D the pipe (inside) diameter. f stands for the Darcy friction factor. Its value depends on the flow's Reynolds number Re and on the pipe's relative roughness ε / D.
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.
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.
This relative movement generates fluid friction, which is a factor in developing turbulent flow. Counteracting this effect is the viscosity of the fluid, which tends to inhibit turbulence. The Reynolds number quantifies the relative importance of these two types of forces for given flow conditions and is a guide to when turbulent flow will ...
From the chart, it is evident that the friction factor is never zero, even for smooth pipes because of some roughness at the microscopic level. The friction factor for laminar flow of Newtonian fluids in round tubes is often taken to be: [4] = [5] [2] where Re is the Reynolds number of the flow.
Drag coefficients in fluids with Reynolds number approximately 10 4 [1] [2] Shapes are depicted with the same projected frontal area. In fluid dynamics, the drag coefficient (commonly denoted as: , or ) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water.
Very hard steel (e.g. chisels, quality knife blades): HRC 55–66 (Hardened High Speed Carbon and Tool Steels such as M2, W2, O1, CPM-M4, and D2, as well as many of the newer powder metallurgy Stainless Steels such as CPM-S30V, CPM-154, ZDP-189. There are alloys that hold a HRC upwards 68-70, such as the Hitachi developed HAP72.