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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 and power number fall from the above analysis if , n, and D are chosen to be the basis variables. If, instead, μ {\textstyle \mu } , n , and D are selected, the Reynolds number is recovered while the second dimensionless quantity becomes N R e p = P μ D 3 n 2 {\textstyle N_{\mathrm {Rep} }={\frac {P}{\mu D^{3}n^{2}}}} .
The power number N p (also known as Newton number) is a commonly used dimensionless number relating the resistance force to the inertia force. The power-number has different specifications according to the field of application. E.g., for stirrers the power number is defined as: [1] = with
Hydrodynamic stability is a series of differential equations and their solutions. A bifurcation occurs when a small change in the parameters of the system causes a qualitative change in its behavior,. [1] The parameter that is being changed in the case of hydrodynamic stability is the Reynolds number.
The Reynolds number is the ratio of inertial forces to viscous forces within a fluid that is subjected to relative internal movement due to different fluid velocities. A region where these forces change behavior is known as a boundary layer, such as the bounding surface in the interior of a pipe.
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 Reynolds and Womersley Numbers are also used to calculate the thicknesses of the boundary layers that can form from the fluid flow’s viscous effects. The Reynolds number is used to calculate the convective inertial boundary layer thickness that can form, and the Womersley number is used to calculate the transient inertial boundary thickness that can form.
In addition to reducing the number of parameters, non-dimensionalized equation helps to gain a greater insight into the relative size of various terms present in the equation. [1] [2] Following appropriate selecting of scales for the non-dimensionalization process, this leads to identification of small terms in the equation. Neglecting the ...