Poiseuille's Equation Calculator

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Poiseuille's Equation Calculator

Poiseuille's Equation calculator is used to calculate the flow rate in volume per second using Poiseuille's law.

Importance of Poiseuille's Equation

Poiseuille's equation, named after the French physicist Jean Louis Marie Poiseuille, is of paramount importance in fluid dynamics. It provides a mathematical relationship between pressure, flow rate, viscosity, and the physical properties of the pipe.

By using Poiseuille's equation, engineers and scientists can determine the flow rate of a fluid through a pipe, predict pressure drops, and optimize system designs.

How to derive Poiseuille's Equation?

To derive Poiseuille's equation, let's consider a cylindrical pipe with length 'L,' radius 'r,' and a viscous fluid flowing through it. Poiseuille's equation states that the volumetric flow rate 'Q' is directly proportional to the pressure difference 'ΔP' and the fourth power of the radius, and inversely proportional to the viscosity 'μ' and the length of the pipe 'L.'

Q = (π * ΔP * r4) / (8 * μ * L)

In Poiseuille's equation, several variables and parameters affect the fluid flow. These include the volumetric flow rate (Q), pressure difference (ΔP), pipe radius (r), pipe length (L), and fluid viscosity (μ). Understanding the interplay between these variables is crucial for accurately predicting and controlling fluid flow in practical applications.

Factors Affecting Fluid Flow:

Apart from the variables explicitly mentioned in Poiseuille's equation, several factors influence fluid flow in pipes. These include temperature, surface roughness, compressibility, and non-Newtonian behavior of the fluid.

Understanding these factors and their effects is essential for optimizing fluid flow in various practical applications.

How to solve Poiseuille's Equation?

Example 1:

Consider a cylindrical pipe with a radius (r) of 0.05 meters and a length (L) of 2 meters. The fluid flowing through the pipe has a viscosity (μ) of 0.01 Pascal-seconds. If there is a pressure difference (ΔP) of 1000 Pascals across the pipe. Calculate the volumetric flow rate (Q) using Poiseuille's Equation.


Step 1: Extract the data:

Radius = r = 0.05 meters

Length = l = 2 meters

Viscosity = μ = 0.01 Pascal-seconds

Pressure difference = ΔP = 1000 Pa

Step 2: Calculation

Q = (π * ΔP * r4) / (8 * μ * L)

Q = {π * 1000 * (0.05)4} / (8 * 0.01 * 2)

Q = (3.1416 * 1000 * 0.00000625) / 0.16

Q = 0.19635 m3/s

Example 2:

Let's consider another cylindrical pipe with a radius (r) of 0.02 meters and a length (L) of 1 meter. This time, the fluid has a higher viscosity (μ) of 0.1 Pascal-seconds. If the pressure difference (ΔP) across the pipe is 500 Pascals, what will be the volumetric flow rate (Q)?


Step 1: Extract the data:

Radius = r = 0.02 meters

Length = l = 1 meters

Viscosity = μ = 0.1 Pascal-seconds

Pressure difference = ΔP = 500 Pa

Step 2: Calculation

Q = (π * ΔP * r4) / (8 * μ * L)

Q = {π * 500 * (0.02)4} / (8 * 0.1 * 1)

Q = (3.1416 * 500 * 0.0000016) / 0.8

Q = 0.00987 m3/s

These numerical examples demonstrate how Poiseuille's Equation can be used to calculate the volumetric flow rate of fluids through pipes, considering different pipe dimensions, pressure differences, and fluid viscosities.

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