Regression analysis and curve fitting for the hydrodynamic coefficients of an underwater vehicle undergoing straight-ahead motion

This paper presents the regression analysis for the hydrodynamic coefficients of the bare hull configuration of a generic underwater vehicle hullform, the SUBOFF undergoing straight-ahead motion at different submergence depths relative to the free surface. The datapoints for the regression analysis were obtained using Computational Fluid Dynamics (CFD). The regression analysis used the Curve Fitting Toolbox from MATLAB and employed several methods to obtain the optimal empirical equations to describe the hydrodynamic coefficients with respect to forward speed and submergence depth in the form piecewise functions due to the different complex regimes observed. Each hydrodynamic coefficient was then reconstructed from their respective empirical equations and comparisons were made against an extended CFD datapoints which were not part of the regression process, showing good agreement between CFD datapoints and regression predictions.