# Poiseuille's law is about factors that control the flow rate of fluid through pipe. Explain all the factors involved?

##### 1 Answer

The length and radius of the pipe, as well as the viscosity of the fluid and the flow rate of the fluid all play a role in the required pressure difference across the pipe to maintain flow rate.

#### Explanation:

Suppose that fluid of viscosity

**Important note:**

This Law only holds for laminar flow, ie. flow in which the Reynolds number is less than 1000, ie

where

If the Reynold's number is greater than 1000, then unstable turbulent flow occurs and Poiseulle's Law is no longer valid.