1. What is Reynolds Number?

The Reynolds Number (Re) is a dimensionless quantity used in fluid mechanics to predict flow patterns in different fluid flow situations. It helps determine whether flow will be laminar or turbulent.

2. How Does the Calculator Work?

The calculator uses the Reynolds Number equation:

Where:

• \( \rho \) — Density (kg/m³)
• \( v \) — Velocity (m/s)
• \( D \) — Diameter (m)
• \( \mu \) — Viscosity (Pa·s)

Explanation: The equation calculates the ratio of inertial forces to viscous forces and determines the flow regime of a fluid.

3. Importance of Reynolds Number Calculation

Details: Reynolds Number is crucial for predicting flow patterns, designing piping systems, analyzing aerodynamic flows, and understanding fluid behavior in various engineering applications.

4. Using the Calculator

Tips: Enter density in kg/m³, velocity in m/s, diameter in m, and viscosity in Pa·s. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What Reynolds Number indicates turbulent flow?
A: Generally, Re > 4000 indicates turbulent flow, while Re < 2000 indicates laminar flow. The transition range is between 2000-4000.

Q2: Why is Reynolds Number dimensionless?
A: The units in the numerator and denominator cancel out, making it a pure number without physical dimensions.

Q3: How does pipe roughness affect turbulent flow?
A: In turbulent flow, pipe roughness increases friction factor and pressure drop, while in laminar flow, roughness has minimal effect.

Q4: Can Reynolds Number be used for non-circular pipes?
A: Yes, by using the hydraulic diameter (4 × cross-sectional area / wetted perimeter) instead of the actual diameter.

Q5: What are typical applications of Reynolds Number?
A: Pipe flow design, aircraft design, blood flow analysis, chemical processing, and many other fluid mechanics applications.