1. What is a Water Flow Through a Pipe Calculator?

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

Purpose: It helps engineers, plumbers, and fluid dynamics students understand and predict laminar flow behavior in pipes.

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 Flow Rate Calculation

Details: Accurate flow rate prediction is essential for designing plumbing systems, industrial piping, and understanding fluid dynamics in various applications.

4. Using the Calculator

Tips: Enter pipe radius (in meters), pressure difference (in Pascals), dynamic viscosity (default 0.001002 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 regime does this equation apply to?
A: The Hagen-Poiseuille equation applies only to laminar (not turbulent) flow with Reynolds number below 2100.

Q2: Why is radius to the fourth power?
A: The r⁴ relationship shows how dramatically pipe diameter affects flow rate - doubling the radius increases flow 16-fold.

Q3: What's the default viscosity value?
A: 0.001002 Pa·s is the dynamic viscosity of water at 20°C (68°F).

Q4: Can I use this for other fluids?
A: Yes, but you must use the correct viscosity value for your specific fluid at the operating temperature.

Q5: How does pipe length affect flow?
A: Flow rate is inversely proportional to pipe length - longer pipes have greater resistance and lower flow rates.