Analysis of riblets modeling for aeronautical applications

Riblets are drag reduction devices whose effectiveness has been demonstrated by many experiments and reliable numerical simulations. Recent improvements in manufacturing technologies make these devices at a technological level high enough to be applied to the next generation aircraft. Even if riblets effectiveness is ensured, their performance on practical aeronautical configuration are difficult to be computed by numerical analyses due to their dimensions (microns for aviation applications) that would require Direct Numerical Simulation (DNS) still unfeasible for complex shapes at high Reynolds numbers. In the recent years some models for Reynolds Averaged Navier Stokes (RANS) methods or Large Eddy Simulations (LES) have been developed that are able to analyze riblets effect also on full aircraft configurations. In the present paper two models developed by the authors are analyzed and compared also presenting recent developments. The sensitivity to different solver is also discussed. Aircraft configuration analyses are presented showing some interesting and unexpected effect of riblets.