1. What is a Pipe Flow Calculator?

Definition: This calculator computes the volumetric flow rate of a fluid through a cylindrical pipe using the Hagen-Poiseuille equation.

Purpose: It helps engineers, physicists, and students determine fluid flow characteristics in laminar flow conditions.

2. How Does the Calculator Work?

The calculator uses the Hagen-Poiseuille equation:

Where:

• \( Q \) — Volumetric flow rate (m³/s)
• \( r \) — Pipe radius (m)
• \( \Delta P \) — Pressure difference (Pa)
• \( \mu \) — Dynamic viscosity (Pa·s)
• \( L \) — Pipe length (m)

Explanation: The flow rate is directly proportional to the pressure difference and the fourth power of the radius, and inversely proportional to viscosity and pipe length.

3. Importance of Pipe Flow Calculation

Details: Accurate flow calculations are essential for designing plumbing systems, industrial piping, medical devices, and understanding fluid dynamics.

4. Using the Calculator

Tips: Enter the pipe radius in meters, pressure difference in Pascals, dynamic viscosity (default 0.001 Pa·s for water at 20°C), and pipe length in meters. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What flow regimes does this equation apply to?
A: The Hagen-Poiseuille equation is valid only for laminar (not turbulent) flow in long, straight, circular pipes.

Q2: What's a typical viscosity value for water?
A: Water at 20°C has a viscosity of about 0.001 Pa·s. This decreases with increasing temperature.

Q3: Why does radius have such a large effect (r⁴)?
A: The r⁴ relationship shows that small changes in pipe diameter dramatically affect flow rate due to reduced friction near the walls.

Q4: What units should I use?
A: Use consistent SI units: meters for length, Pascals for pressure, and Pa·s for viscosity to get m³/s flow rate.

Q5: Can I use this for gases?
A: Only for very slow gas flows. Gases typically have much lower viscosity and often exhibit compressibility effects.