Poiseuilleeksperimenter

Poiseuilleeksperimenter is a term used in the history of fluid dynamics to describe researchers who perform experiments based on Poiseuille's law to study laminar flow in cylindrical conduits. The designation draws on Jean Léonard Marie Poiseuille, whose experiments established how pressure, tube radius, fluid viscosity, and length determine flow rate. In practice, a Poiseuilleeksperimenter investigates steady, incompressible Newtonian fluids in long, straight tubes and compares observed flow with the Hagen–Poiseuille relation.

According to Hagen–Poiseuille law, the volumetric flow rate Q through a circular tube of radius r and length L under a pressure difference ΔP is Q = (π ΔP r^4) / (8 μ L). The flow is laminar and there is a parabolic velocity profile. The law requires no-slip at the wall, negligible entrance effects, and a Newtonian fluid.

Typical apparatus include a reservoir or hydrostatic head to provide ΔP, a selection of capillary tubes with known dimensions, a method to measure Q (timed collection or flowmeter), and a means to determine viscosity μ. In microfluidics and physiology, Poiseuille-type measurements are used to calibrate devices, study blood flow in vessels, and model fluid transport in channels.

Limitations include non-Newtonian fluids, turbulent regimes, short or curved tubes where entrance effects dominate, and deviations due to real fluids or surface roughness. The concept remains foundational in teaching and in the design of piping, metering devices, and microfluidic systems, linking geometry, viscosity, and pressure to transport rates.