The experiment shows that when the fluid moves in a horizontal circular tube in laminar flow, its volume flow Q has the following relations with the pressure difference Δ p between the two ends of the tube, the radius r, the length l of the tube, and the viscosity coefficient η of the fluid: Q = π× R 4× η P/(8 η L), which is the famous Poiseuille's law. Let r = 8 η l/(π r 4), that is, q = δ p/r, and r is called flow resistance.
App application
Poiseuille's law q =πr 4xδP/8ηl describes the relationship between the flow rate q and the pressure difference δP between the two ends of the pipeline, the pipeline radius r0, the pipeline length l and the fluid viscosity coefficient η when the incompressible viscous fluid flows stably in a horizontal circular pipe with small Reynolds number and laminar flow pattern. Poiseuille's law is an important law of fluid dynamics, which is often used to determine the viscosity coefficient of fluid, blood flow analysis, drug analysis and preparation, and is a physical knowledge of interest to medical students and pharmaceutical students.