Poiseuilletörvény

Poiseuilletörvény, also known as Poiseuille's Law, describes the pressure drop in a fluid flowing through a cylindrical pipe. It states that the volume flow rate of a Newtonian fluid is directly proportional to the pressure difference and the fourth power of the pipe's radius, and inversely proportional to the fluid's viscosity and the pipe's length. Mathematically, it is expressed as Q = (π * ΔP * r^4) / (8 * η * L), where Q is the flow rate, ΔP is the pressure difference, r is the pipe radius, η is the dynamic viscosity, and L is the pipe length.

This law is a fundamental concept in fluid dynamics and has significant applications in various fields. For instance, it is crucial in understanding blood flow in arteries and veins, where the radius of blood vessels can change. It also plays a role in engineering, such as in designing pipelines for oil and gas transportation, or in the flow of liquids through laboratory equipment. The law assumes laminar flow, meaning the fluid moves in smooth layers without significant mixing. If the flow becomes turbulent, Poiseuille's Law is no longer directly applicable, and other more complex models are required. The derivation of Poiseuille's Law involves applying principles of fluid mechanics and considering the shear stress within the fluid.