Question

Explain (in your own words) what is achieved by Reynolds averaging the Conservation of Momentum equations. Include a description of what the Reynolds stress terms account for and where they come from.

Answer 1

We know that, the Reynolds number indicates the flow of the fluid. Reynolds number depends on the velocity of the fluid. The Reynolds number is an instantenous property. Hence to study the time based proprties of motion of fluid flow, the reynolds number is averaged with navier-stokes equation. Reynolds number also posses some stresses within the fluid called as Reynolds stress. the reynolds stress is the component of the total stress. The reynolds stress is obtained by averaging the the navier-stokes equation.

The Reynolds stress accounts for turbulent fluctuations present in the fluid.