When calculating friction loss for laminar flow, which formula should be used?

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Multiple Choice

When calculating friction loss for laminar flow, which formula should be used?

Explanation:
When calculating friction loss for laminar flow in a circular pipe, the correct formula is derived from the principles of fluid mechanics, specifically the behavior of fluids under laminar conditions. Laminar flow, defined by a Reynolds number less than approximately 2000, results in a smooth, orderly movement of fluid layers. The formula f = 64/Re is established from the Hagen-Poiseuille equation, which describes the pressure drop due to viscosity in laminar flow. In this context, 'f' refers to the Darcy-Weisbach friction factor, and 'Re' refers to the Reynolds number. This relationship indicates that as the Reynolds number increases, the friction factor decreases, which aligns with the understanding that higher flow rates reduce relative viscosity effects. The significance of the factor 64 in the formula arises from the derivation that considers the flow’s behavior in a cylindrical geometry, accounting for how viscous forces dominate under laminar conditions. This concept is fundamental in fluid dynamics and important for accurately predicting flow behavior and pressure drops in civil engineering applications, such as water supply and distribution systems.

When calculating friction loss for laminar flow in a circular pipe, the correct formula is derived from the principles of fluid mechanics, specifically the behavior of fluids under laminar conditions. Laminar flow, defined by a Reynolds number less than approximately 2000, results in a smooth, orderly movement of fluid layers.

The formula f = 64/Re is established from the Hagen-Poiseuille equation, which describes the pressure drop due to viscosity in laminar flow. In this context, 'f' refers to the Darcy-Weisbach friction factor, and 'Re' refers to the Reynolds number. This relationship indicates that as the Reynolds number increases, the friction factor decreases, which aligns with the understanding that higher flow rates reduce relative viscosity effects.

The significance of the factor 64 in the formula arises from the derivation that considers the flow’s behavior in a cylindrical geometry, accounting for how viscous forces dominate under laminar conditions. This concept is fundamental in fluid dynamics and important for accurately predicting flow behavior and pressure drops in civil engineering applications, such as water supply and distribution systems.

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