**Introduction**

The standard pressure boundary conditions for compressible flow fix speci fic flow variables at the boundary (e.g., static pressure at an outlet boundary).

As a result, pressure waves incident on the boundary will reflect in an unphysical manner, leading to local errors. The effect are more pronounced for internal flow problems where boundaries are usually close to geometry inside the domain, such as compressor or turbine blade rows.

The turbo-specfiic non-reflecting boundary conditions (NRBCs) permit waves to pass through the boundaries without spurious reflections. The method used in FLUENT is based on the Fourier transformation of solution variables at the non-reflecting boundary.

This tutorial demonstrates how to do the following:

- Set up and solve the turbine blade flow field using the standard pressure outlet boundary treatment -

- Activate the turbo-specific NRBCs and solve the problem again

- Compare the results for the standard and non-reflecting pressure boundaries