1. What is Critical Velocity of Liquid?

Definition: Critical velocity is the maximum velocity at which a fluid flow transitions from laminar to turbulent flow.

Purpose: This calculation is essential in fluid dynamics for designing pipes, channels, and other systems where flow characteristics are important.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( V_c \) — Critical velocity (m/s)
• \( Re \) — Reynolds number (unitless)
• \( \eta \) — Dynamic viscosity (Pa·s)
• \( \rho \) — Fluid density (kg/m³)
• \( D \) — Characteristic diameter (m)

Explanation: The formula determines the velocity at which the flow transitions based on fluid properties and system dimensions.

3. Importance of Critical Velocity Calculation

Details: Knowing the critical velocity helps engineers design systems to maintain desired flow regimes, optimize energy consumption, and prevent unwanted turbulence.

4. Using the Calculator

Tips: Enter the Reynolds number, fluid viscosity, fluid density, and characteristic diameter. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical Reynolds number for transition?
A: For pipe flow, transition typically occurs around Re = 2300, but this can vary based on system conditions.

Q2: How do I determine viscosity?
A: Viscosity values can be found in fluid property tables or measured experimentally for specific fluids.

Q3: What is characteristic diameter?
A: For pipes, it's the inner diameter. For non-circular channels, use the hydraulic diameter.

Q4: Does temperature affect critical velocity?
A: Yes, temperature affects viscosity and density, which in turn affect critical velocity.

Q5: What happens above critical velocity?
A: Flow becomes turbulent, with increased mixing, energy dissipation, and different pressure drop characteristics.