Computational study on an Ahmed Body equipped with simplified underbody diffuser

The Ahmed body is one of the most studied 3D automotive bluff bodies and variation its slant angle rear upper surface generates different flow behaviours, similar to a standard road vehicles. In this study we extend geometrical evaluate influence underbody diffuser which are commonly applied in high performance race cars improve downforce. Parametric studies performed on two baseline configurations body: first with 0° second 25° angle. We employ high-fidelity CFD simulation based spectral/hp element discretisation that combines classical mesh refinement polynomial expansions order achieve both better accuracy. length was fixed same 222 ?mm top have previously been studies. changed from 50° increments 10° an additional case considering 5°. proposed methodology validated angle, found difference for drag lift coefficients 13% 1%, respectively. For peak values negative (downforce) coefficient were achieved 30° where fully attached streamwise vortical structures, analogous results obtained [1] but flipped upside down. angles above 30°, separated diffuser. achieves value downforce at 20° has vortices combined some separation. becomes separated. • application method allowed solution relatively coarse mesh. Stable iLES-SVV using Reynolds number novel CG-SVV DGkernel. Presence leads increment, hence effective squared-back shows up 30°. increment while decreases 20°.