Hydrodynamic characteristics of the blue whale in unbounded and density-stratified flow environments

Based on the realizable k-epsilon turbulence model and the Volume of Fluid (VOF) method, this article investigates the hydrodynamic characteristics of blue whales in both unbounded and density-stratified flow environments. The results demonstrate that in unbounded flow, the drag coefficient of a blue whale fin is most significantly influenced by fluid velocity, and it decreases by 17.27% as the velocity increases. In density-stratified flow, the amplitude of the internal wave increases with the Froude number while its angle decreases. Wave-making drag rises with the whale's proximity to the interface. The wave-making drag coefficient is highly sensitive to density variations; when the lower layer density increases from 1020 kg/m3 to 1040 kg/m3, the wave-making drag coefficient increases by 154.36%. This study provides important insights into the hydrodynamic characteristics of underwater creatures in a density-stratified flow environment, offering valuable references for the development of biomimetic designs and technologies.