What is reynolds averaged navier stokes?

Reynolds-averaged Navier Stokes (RANS) equations are a set of equations that describe the behavior of fluid flow in terms of averages over time and spatial scales. They are derived from the Navier-Stokes equations by decomposing the flow variables into the time-averaged mean and fluctuating components.

RANS equations are commonly used in computational fluid dynamics (CFD) to simulate turbulent flows, as they provide a balance between computational efficiency and accuracy in modeling turbulent processes. They are particularly useful for industrial applications where turbulent flows play a significant role, such as in aerodynamics, hydrodynamics, and combustion processes.

One of the key assumptions made in RANS equations is the introduction of turbulence models to parameterize the effect of turbulence on the flow variables. These turbulence models are based on empirical correlations and provide closure for the time-averaged equations, allowing for the calculation of turbulent quantities such as turbulence kinetic energy and Reynolds stresses.

Overall, RANS equations offer a practical and effective way to simulate turbulent flows in engineering applications, providing valuable insights into complex flow phenomena and aiding in the design and optimization of engineering systems. However, it is important to note that RANS models have limitations and may not be suitable for all types of turbulent flows, especially those with strong unsteadiness or significant interactions between different scales of turbulence.