How to use the poiseuille flow calculator
Flow rate for viscous fluid through a narrow tube. Enter tube radius, tube length, pressure drop, viscosity in the fields above; the flow rate is computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- r — Tube radius (mm)
- L — Tube length (m)
- dP — Pressure drop (Pa)
- mu — Viscosity (Pa·s)
Worked example
With tube radius = 1 mm, tube length = 0.5 m, pressure drop = 1000 Pa, viscosity = 0.001 Pa·s, the calculator gives flow rate ≈ 0.7853982 mL/s.
Frequently asked questions
What is the formula for the poiseuille flow calculation?
Flow rate (mL/s) = π × (r / 1000)^4 × dP / (8 × mu × L) × 1e6. Here r is tube radius (mm), L is tube length (m), dP is pressure drop (Pa), mu is viscosity (Pa·s).
What inputs do I need for the poiseuille flow calculator?
You need tube radius in mm, tube length in m, pressure drop in Pa, viscosity in Pa·s. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.