Isolating fast and slow flows in three-dimensional fluid dynamics

The study on isolating fast and slow flows in three-dimensional fluid dynamics models a speech-related air puff using Large Eddy Simulation (LES) in COMSOL Multiphysics 6.1. Air impacts a simulated face placed 30 cm from the speaker, solving transient incompressible Navier–Stokes equations (with Boussinesq approximation) alongside a heat-balance equation. The simulation starts at 20°C with zero velocity, uses a generalized alpha time-stepping scheme, and applies a relative tolerance of 0.001. Turbulence is handled via an RBVM LES model, with turbulent heat transfer represented by a user-defined turbulent Prandtl number of 0.85. The inlet lip aperture is modeled as an ellipse with 15 mm and 2 mm semi-axes, and exhaled air is set at 37°C while the face surfaces use 33°C. Computational results use a mesh of 0.1226 m volume and 2,242,827 elements, after adaptive refinement. Springer Nature reports neutrality on jurisdictional claims.