This study presents a structured approach to the aerodynamic evaluation of
commercial heavy-duty vehicles by categorizing the underlying flow physics into
three primary phenomena: pressure-induced separation, geometry-induced
separation, and flow diffusion. Furthermore, the study gives insights into the
benefits of Detached Eddy Simulations (DES) over traditional Reynolds-Averaged
Navier–Stokes (RANS) approaches by analyzing the flow behavior in cases that
correspond to these phenomena. Fundamental insights on pressure and
geometry-induced separation were developed through simulations of flow over a
sphere and a rectangular cylinder at a Reynolds number of 2.8 × 106.
Additionally, flow diffusion was investigated using a coaxial jet interacting
with surrounding fluid at a Reynolds number of 2.1 × 104. These cases
were analyzed using three turbulence modeling techniques:
k-ε, k-ω
SST, and DES.
To demonstrate the practical relevance of these phenomena, a comprehensive
aerodynamic performance study was conducted on a commercial heavy-duty truck.
This final analysis integrates all three flow behaviors, showcasing their
combined impact on vehicle aerodynamics. The study emphasizes the effectiveness
of the DES approach in capturing complex flow structures with enhanced accuracy.
Furthermore, this study provides meshing guidelines for near-wall and wake
dominant regions, to be implemented in DES-based simulations. The findings aim
to support future research by offering a robust framework for applying advanced
turbulence models in real-world aerodynamic evaluations.
