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The Skin Friction Drag Coefficient (Cf) is obtained by dividing the skin friction drag by the product of dynamic pressure and reference area. It quantifies the drag caused by fluid viscosity acting tangentially to a surface.
The calculator uses the formula for laminar flow over a flat plate:
Where:
Explanation: This formula applies specifically to laminar boundary layer flow over a flat plate and shows that skin friction drag decreases with increasing Reynolds number.
Details: Accurate calculation of skin friction drag is crucial for aerodynamic and hydrodynamic design, performance prediction of vehicles and structures, and optimizing energy efficiency in fluid systems.
Tips: Enter the Reynolds Number for Laminar Flow. The value must be positive and valid for laminar flow conditions (typically ReL < 5×105 for flat plates).
Q1: What is the range of validity for this formula?
A: This formula is valid for laminar flow over a flat plate, typically for Reynolds numbers below 5×105.
Q2: How does skin friction drag differ from pressure drag?
A: Skin friction drag results from viscous shear forces parallel to the surface, while pressure drag results from normal pressure forces due to flow separation.
Q3: What factors affect skin friction drag?
A: Surface roughness, fluid viscosity, flow velocity, and surface area are the primary factors affecting skin friction drag.
Q4: Why does skin friction decrease with increasing Reynolds number?
A: At higher Reynolds numbers, the boundary layer becomes thinner relative to the characteristic length, reducing the velocity gradient and thus the shear stress.
Q5: How is this different from turbulent flow skin friction?
A: Turbulent flow has higher skin friction due to increased mixing and momentum transfer, typically described by different empirical relations.