A Review of Solution Stabilization Techniques for RANS CFD Solvers

Abstract

Nonlinear, time-linearized and adjoint Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) solvers are widely used to assess and improve the aerodynamic and aeroelastic performance of aircrafts and turbomachines. While RANS CFD solver technologies are relatively mature for applications at design conditions where the flow is benign, their use in off-design conditions, featuring flow instabilities, such as separations and shock wave/boundary layer interactions, still faces many challenges, with tight residual convergence being a major difficulty. To cope with this, several solver stabilization techniques have been proposed. However, a systematic and comparative study of these techniques has not been reported, to some extent hindering the wide deployment of these methods for industrial applications. In this paper, we critically review the existing methods for solver convergence stabilization, with the main purpose of explaining the rationale behind the algorithms and providing a systematic view of the seemingly different methods. Specifically, mathematical formulations and implementation details of these methods, example applications, and the pros and cons of the methods are discussed in detail, along with suggestions for further improvements. This review is expected to give CFD method developers an overview of the various solution stabilization methods and application engineers an idea how to choose a suitable method for their respective applications.

Comparing Turbulence Models for CFD Simulation of UAV Flight in a Wind Tunnel Experiments

“…The simplification of the incompressible flow is very reasonable, since the compression effects of the Mach number (0.11655) are low, it is small enough to be neglected at mach numbers below (0.3). Flow is assumed to be adiabatic, which means there is no heat exchange between The best practice guidelines, provided by (Xu, et al, 2023), were followed, 3D two dominoes have been created around the drone model to represent the area in which the wind tunnel (it is a specifically created, protected area into which air is drawn, or blown, mechanically to a predetermined speed and flow pattern at a specific moment) (Roomi, 2016) experiment is to be tested Its dimensions are shown in Fig. 2.…”