Aerodynamic Subsonic Model at Transitional/Turbulent Reynolds Number for Bluff-Ellipsoidal Hulls

The present work addresses the subsonic aerodynamic coefficients model for bluff ellipsoidal hulls at transitional and turbulent Reynolds number. The drag, lift, and moment aerodynamic coefficients model are based on computational fluid dynamics (CFD) simulations for four bluff ellipsoids with aspect ratio of 1, 2, 3, and 4, in the Reynolds number range of 1 × 103 to 2 × 106 and angle of attack range from 0 to 20 degrees. The Large Eddy Simulation (LES) turbulence model is used with the sub-grid turbulence model Wall-Adapting Local-Eddy Viscosity (WALE) to solve the fluid field. To reduce computational simulation time, at a first instant, the mesh is gradually refined until the point that it does not influence anymore in the final result (mesh independence). For each aerodynamic coefficient a nonlinear equation structure, valid for all the ellipsoids, is proposed as a parametric model with parameters estimated using the least mean square algorithm applied to the results of the computational fluid dynamics simulations. The proposed equations have a superior performance, in terms of precision and number of terms, when compared to polynomial equations fitted to the same data.