Linear Stability-Based Smooth Reynolds-Averaged Navier-Stokes Transition Model for Aerodynamic Flows

The inclusion of transition to turbulence effects in computational fluid dynamics simulations makes it possible to design laminar flow airframes. It also increases the level of physical representations for simulations of standard airframes because laminar flow regions may be present in parts of the aircraft in multiple flight conditions. Modified Reynolds-averaged Navier-Stokes (RANS) models that consider transition effects became popular in the last decade and indicated favorable agreement with experimental data. However, these models present more difficult convergence behavior when compared with fully turbulent RANS approaches. To address this issue, an approximate Newton-Krylov solver is leveraged to solve the transitional flow over aeronautical configurations using a flow-stability-based, smooth RANS transition model. The amplification factor transport (AFT) model is modified to create a smooth variant, referred to as AFT-S. Strategies have been developed to obtain representative physical solutions that exhibit good agreement with experimental data. The convergence behavior for the transition RANS model is also addressed, and its impact on the numerical results is assessed. These results constitute the first in-depth investigation on the numerical behavior of an AFT-type transition model.