1. What is the Pipe Flow Calculator?

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

Purpose: It helps engineers and fluid dynamics professionals determine flow characteristics in pipe systems.

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 equation describes laminar flow of an incompressible Newtonian fluid in a long cylindrical pipe.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate prediction is essential for pipe system design, pump selection, and process engineering applications.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What types of flow does this equation apply to?
A: The Hagen-Poiseuille equation applies only to laminar (not turbulent) flow in long, straight pipes.

Q2: How does pipe radius affect flow rate?
A: Flow rate is proportional to the fourth power of the radius - small radius changes create large flow rate changes.

Q3: What's a typical viscosity value for water?
A: Water at 20°C has viscosity of about 0.001 Pa·s, which is set as the default value.

Q4: Does this account for pipe roughness?
A: No, the equation assumes smooth pipes and doesn't account for surface roughness effects.

Q5: What's the Reynolds number limit for this equation?
A: Typically valid for Reynolds numbers below 2100 (laminar flow regime).