# About the fluid friction along the wall in pipes

I wonder how can the friction between a fluid and a wall in a cylindrical pipe can be calculated. Is there any theory that I can refer to? I also want to check if there's any relation between the diameter of the pipe, the velocity and the temperature of the fluid and friction.

## 1 Answer

We know that adhesive forces bound fluid particles at the surface of the pipe. The rest of the fluid will not be affected by this force. But force acting on the remaining fluid is viscous force. The below figure shows relationship between velocity profile and radius of pipe. Where n is coefficient of viscosity.

Even if the fluid is a gas, we can still see the effects of viscous and frictional forces at the surface of the pipe, but with different values.

• Your last paragraph is incorrect. Gases behave the same way that liquids do. They just have different values of density, viscosity, etc. Commented Jun 5, 2022 at 17:09
• Ha yes, Thanks for that! Commented Jun 7, 2022 at 6:32