Corrections for the drag on submarines due to the blockage effect

Abstract

A numerical investigation of the drag on submarines close to the seabed was conducted. The objective was to obtain velocity corrections to account for the additional drag caused by the blockage effect. A simulation model to estimate drag of a submarine hull was built using the open source code OpenFOAM. Numerical errors due to grid refinement were assessed and simulations were validated through comparisons with experimental data. The analyzed Reynolds numbers ranged from 5×106 to 2.5×107. Results showed good agreement with experimental drag coefficients for open water conditions, with maximum deviation of 3.25% for the lowest Reynolds number. To assess the effect of the proximity to the bottom wall, four model-to-wall distances were considered. Results showed a prominent effect on the pressure drag components and were used to propose two types of velocity correction for the blockage effect. The proposed correlations successfully corrected the pressure coefficient towards the open water values.