Moody Friction Factor Calculator 
Calculation uses an equation that simulates the Moody Diagram. Turbulent or laminar flow. 

D = Diameter of a circular duct. If duct is noncircular, then D is computed as the hydraulic diameter of a rectangular duct, where D = 4A / P per our noncircular duct page. Kinematic viscosity (v) depends on the fluid (water, air,
etc.). Click for table. The equations used in this program represent the Moody diagram which is the oldfashioned way of finding f. You may enter numbers in any units, so long as you are consistent. (L) means that the variable has units of length (e.g. meters). (L^{3}/T) means that the variable has units of cubic length per time (e.g. m^{3}/s). The Moody friction factor (f) is used in the DarcyWeisbach major loss equation. Note that for laminar flow, f is independent of e. However, you must still enter an e for the program to run even though e is not used to compute f. Equations can be found in Discussion and References for Closed Conduit Flow. A more complicated equation which represents a slightly larger range of Reynolds
numbers and e/D's is used in Design of Circular Liquid or Gas
Pipes. © 19992023 LMNO Engineering, Research, and Software, Ltd. All rights reserved. Please contact us for consulting or questions about Moody friction factor. LMNO Engineering, Research, and Software, Ltd. 
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