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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.
The roughness length is one of many possible measures of the roughness of a surface. For example, in classical mechanics the coefficient of friction is commonly used to measure the roughness of a surface as it relates to the force exerted on another contacted object.
C is a roughness coefficient; R is the hydraulic radius (in ft for US customary units, in m for SI units) S is the slope of the energy line (head loss per length of pipe or h f /L) The equation is similar to the Chézy formula but the exponents have been adjusted to better fit data from typical engineering situations.
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.
Roughness progression for a road in Texas, US. Blue dots show the times of maintenance. The international roughness index (IRI) is the roughness index most commonly obtained from measured longitudinal road profiles. It is calculated using a quarter-car vehicle math model, whose response is accumulated to yield a roughness index with units of ...
The Gauckler–Manning coefficient, often denoted as n, is an empirically derived coefficient, which is dependent on many factors, including surface roughness and sinuosity. When field inspection is not possible, the best method to determine n is to use photographs of river channels where n has been determined using Gauckler–Manning's formula.
For stubborn calluses, this formula packs more of a punch: it has three times the concentration of urea than the brand’s Roughness Relief Body Lotion. The targeted spot treatment tip also makes ...
Most charts or tables indicate the type of friction factor, or at least provide the formula for the friction factor with laminar flow. If the formula for laminar flow is f = 16 / Re , it is the Fanning factor f, and if the formula for laminar flow is f D = 64 / Re , it is the Darcy–Weisbach factor f D.