Investigation of instabilities in compressible flow (UNSTIK)

Purpose and goal:

The aim was to develop and validate a higher order linear solver including a method for global instability modes and to validate it against test cases from the literature.

One goal was to deliver the developed code for future studies of phenomena such as buffeting on aircraft configurations. Another goal was to complete the doctoral program that was started in the LaFloDeS NFFP-2019-05369 project. The doctoral student defended his thesis, "Numerical investigation of bypass transition and its control" 2024-06-14 with positive results.

Expected results and effects:

The result is that a higher-order linear solver, including a method for global instability modes, has been developed and validated within the project.

The expected effect is that more accurate studies of phenomena such as buffeting and flow in cavities on aircraft configurations can be performed in the future. Approach and implementation:

Saab has been project manager and KTH has been the main developer. An existing open CFD programme has been used as a starting point and modified for the purposes of the project. Validation of the resulting method has been performed for two cases, partly for a flat plate and partly for a NACA 0012 airfoil.

Global stability studies for a cavity have been carried out during the project for both an incompressible and a compressible case. The PHD student at KTH ended the project by defending his thesis "Numerical investigation of bypass transition and its control" 2024-06-14 with positive results.