Mesh sensitivity and turbulence resolution in STAR-CCM+

Project · Project 15

A detailed CFD study of subsonic flow (M = 0.42, Re = 10⁶) around a bluff body using STAR-CCM+, focusing on mesh sensitivity and near-wall turbulence resolution through systematic variation of prismatic layer discretization.

Method

Polyhedral meshes were generated with increasing boundary layer refinement, sweeping from 1 to 6 prism layers, and their impact evaluated on wall-resolved parameters (y+), aerodynamic force coefficients, and solution convergence.

Polyhedral mesh with prism layers around the bluff body/assets/img/projects/starccm-mesh.png

Fig. 1 — Polyhedral mesh with boundary layer refinement.

Results

Increasing the layer count produced a clear reduction in y+ values, from 433 down to 79, improving boundary layer resolution and physical fidelity. Meanwhile the force coefficients converged towards a stable value of 2.5×10⁻³, indicating mesh independence had been reached.

y+ values as a function of prism layer count/assets/img/projects/starccm-yplus.png

Fig. 2 — Min and max y+ vs. number of layers.

Force coefficient convergence with layer count/assets/img/projects/starccm-force-coeff.png

Fig. 3 — Force coefficient vs. number of layers.

A parallel performance study was additionally conducted, analysing solver scalability across multiple processors (2 to 8 cores) and mesh sizes, identifying non-linear efficiency behaviour and demonstrating the trade-off between computational cost and mesh resolution.