The purpose of this study is to clarify the mechanisms governing the hydrodynamic and thermal wake characteristics of self-propelled submarines in density-stratified oceans, which is of practical significance for non-acoustic detection. Unlike previous studies that treated hydrodynamic and thermal wakes separately, this study couples both effects under three representative stratification types that are strong, continuous, and mixed layers by using the Defense Advanced Research Projects Agency SUBOFF submarine model. Delayed detached eddy simulation is employed to examine wake dynamics at varying speeds and depths, focusing on turbulent structures and thermal signatures. Results indicate that near-surface operation leads to a pronounced upward migration of the thermal wake, which becomes more evident at lower speeds. At shallow depths (10 m), distinct temperature anomalies can even be observed near the surface, whereas at greater depths (≥20 m), such differences are no longer visible. When the submarine navigates above or within the pycnocline, strong mixing occurs along with energetic internal waves. At 15 kn and 10 m depth, the surface thermal signature varies significantly with stratification type. A pronounced hot wake emerges in the condition of strongly stratified and mixed layers. As in the condition of continuously stratified waters, an opposite cold wake phenomenon appears. These findings highlight how density stratification, navigation depth, and speed collectively determine the persistence and detectability of submarine wakes, which providing valuable guidance for the development of non-acoustic detection technologies.
Lu et al. (Thu,) studied this question.