Poiseuille’s law predicts fully developed laminar flow in a circular tube.
Difficulty
Intermediate
Read time
5 min
Prerequisites
Basic algebra, consistent units, and the stated model assumptions
Source
OpenStax, College Physics 2e, §12.4 (Paul Peter Urone and Roger Hinrichs)OpenFormulaGraph equation reference; FormuLab adaptation details and license are provided below.
Adapted from OpenFormulaGraph, under CC BY 4.0.
FormuLab adapted wording, notation, applicability conditions and topic placement, and expanded the numerical check into a worked example. Example values were adjusted to satisfy the stated model conditions.
Poiseuille’s law predicts fully developed laminar flow in a circular tube. Flow is especially sensitive to radius because radius appears to the fourth power.
| Symbol | Meaning | Units |
|---|---|---|
| Volume Flow Rate | ||
| Pressure (drop) | ||
| Internal tube radius | ||
| Dynamic viscosity | ||
| Tube length |
Estimate volume flow through a narrow tube.
Compare the effect of radius and viscosity.
A long horizontal water tube has radius 0.0100 m, length 2.00 m, viscosity 0.00100 Pa·s, and pressure drop 1.00 Pa. Find its laminar volume flow rate.
OpenFormulaGraph equation reference; FormuLab adaptation details and license are provided below.
Adapted from OpenFormulaGraph, under CC BY 4.0.
FormuLab adapted wording, notation, applicability conditions and topic placement, and expanded the numerical check into a worked example. Example values were adjusted to satisfy the stated model conditions.
Assumptions
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