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Drag Coefficient Equation (Low Reynolds Number):
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The drag coefficient (C_d) is a dimensionless quantity that quantifies the drag or resistance of an object in a fluid environment. For a sphere at low Reynolds numbers, the drag coefficient follows Stokes' law and is inversely proportional to the Reynolds number.
The calculator uses the drag coefficient equation for low Reynolds numbers:
Where:
Explanation: This equation is valid for low Reynolds numbers (typically Re < 0.1) where viscous forces dominate and the flow is laminar around the sphere.
Details: Accurate drag coefficient calculation is crucial for predicting fluid resistance on spherical objects, designing particle separation systems, analyzing sedimentation rates, and understanding fluid dynamics in various engineering applications.
Tips: Enter the Reynolds number (dimensionless). The value must be valid (Re > 0). This calculator is specifically designed for low Reynolds number flows where Stokes' law applies.
Q1: What is the range of validity for this equation?
A: This equation is valid for low Reynolds numbers, typically Re < 0.1, where viscous forces dominate and the flow is laminar.
Q2: What happens at higher Reynolds numbers?
A: At higher Reynolds numbers, the relationship becomes more complex and different empirical correlations are needed as flow transitions to turbulent regime.
Q3: How is Reynolds number calculated?
A: Reynolds number is calculated as Re = (ρVD)/μ, where ρ is fluid density, V is velocity, D is sphere diameter, and μ is dynamic viscosity.
Q4: What are typical applications of this calculation?
A: This calculation is used in particle dynamics, sedimentation analysis, aerosol science, microfluidics, and various engineering applications involving small particles in fluids.
Q5: Are there limitations to this equation?
A: Yes, this equation is only valid for steady, creeping flow conditions and doesn't account for turbulence, surface roughness, or non-Newtonian fluid behavior.