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Water Pipe Flow Calculator

Flow Rate Formula (Hagen-Poiseuille Equation):

\[ Q = \frac{\pi \times r^4 \times \Delta P}{8 \times \mu \times L} \]

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1. What is a Water Pipe Flow Calculator?

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

Purpose: It helps engineers, plumbers, and fluid dynamics researchers determine water flow in cylindrical pipes under laminar flow conditions.

2. How Does the Calculator Work?

The calculator uses the Hagen-Poiseuille equation:

\[ Q = \frac{\pi \times r^4 \times \Delta P}{8 \times \mu \times L} \]

Where:

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 ensures proper pipe sizing, efficient system design, and meets water supply requirements.

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 (smooth) flow (Re < 2000).

Q2: What's the typical viscosity of water?
A: At 20°C, water has a viscosity of about 0.001002 Pa·s. This decreases with temperature.

Q3: Why is radius to the fourth power?
A: Flow rate is extremely sensitive to pipe diameter because of the parabolic velocity profile in laminar flow.

Q4: Can I use this for turbulent flow?
A: No, for turbulent flow you would need to use the Darcy-Weisbach equation instead.

Q5: How do I convert the result to liters/second?
A: Multiply the result by 1000 (1 m³/s = 1000 L/s).

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