An approach for the estimation of hydrodynamic coefficients of an underwater vehicle in off-design velocities

In this paper, an approach is proposed for the estimation of hydrodynamic coefficients variation as functions of Reynolds number. The variation of rotary damping linear hydrodynamic coefficients for off-design velocities is studied by simulating the rotating arm test and using computational fluid dynamics. Numerical results are validated by comparison with experimental ones reported in the literature for geometry of the well-known underwater vehicle of DARPA SUBOFF and a good agreement is observed. The numerical tool is employed to study the effects of Reynolds number on hydrodynamic coefficients. Numerical results are used for deriving proper functions that estimates hydrodynamic coefficients using truncated power series expansion along with least square method. It can be concluded that it is more appropriate to use fitted functions instead of constant values especially at low Reynolds numbers.