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Figure 1 Hard wheel rolling on and deforming a soft surface, resulting in the reaction force R from the surface having a component that opposes the motion. (W is some vertical load on the axle, F is some towing force applied to the axle, r is the wheel radius, and both friction with the ground and friction at the axle are assumed to be negligible and so are not shown.
Stokes' law is the basis of the falling-sphere viscometer, in which the fluid is stationary in a vertical glass tube. A sphere of known size and density is allowed to descend through the liquid. If correctly selected, it reaches terminal velocity, which can be measured by the time it takes to pass two marks on the tube.
Contents. Moody chart. 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 fD, 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.
μ is the dynamic viscosity of the fluid (Pa·s = N·s/m 2 = kg/(m·s)); Q is the volumetric flow rate, used here to measure flow instead of mean velocity according to Q = π / 4 D c 2 <v> (m 3 /s). Note that this laminar form of Darcy–Weisbach is equivalent to the Hagen–Poiseuille equation, which is analytically derived from the ...
Fanning friction factor. The Fanning friction factor (named after American engineer John T. Fanning) is a dimensionless number used as a local parameter in continuum mechanics calculations. It is defined as the ratio between the local shear stress and the local flow kinetic energy density: [1][2] where.
Traction, traction force or tractive force is a force used to generate motion between a body and a tangential surface, through the use of either dry friction or shear force. [1][2][3][4] It has important applications in vehicles, as in tractive effort. Traction can also refer to the maximum tractive force between a body and a surface, as ...
The capstan equation[ 1 ] or belt friction equation, also known as Euler–Eytelwein formula[ 2 ] (after Leonhard Euler and Johann Albert Eytelwein), [ 3 ] relates the hold-force to the load-force if a flexible line is wound around a cylinder (a bollard, a winch or a capstan). [ 4 ][ 1 ] It also applies for fractions of one turn as occur with ...
Darcy friction factor formulae. In fluid dynamics, the Darcy friction factor formulae are equations that allow the calculation of the Darcy friction factor, a dimensionless quantity used in the Darcy–Weisbach equation, for the description of friction losses in pipe flow as well as open-channel flow. The Darcy friction factor is also known as ...