Objectives  This paper seeks to grasp the influence of a submarine's acceleration and deceleration on its wake spectrum characteristics in stratified flow, and provide a theoretical basis for submarine stealth.

  Methods  The accuracy of CFD technology in simulating the motion of the submerged body making waves on the free surface is first verified, and then analyses are made of the wave-making on the free surface, its convergence and divergence field, and internal wave velocity field under the acceleration and deceleration of a real-scale submarine. By calculating the divergence of the velocity field of the free surface, the influence of submarine acceleration and deceleration on the free surface and jump layer is determined in depth.

  Results  The results show that when the submarine is in unsteady motion, the shear wave and scattered wave distribution of the wake field are completely different from those under uniform motion. Combining the wave height and velocity divergence field, the acceleration and deceleration of the submarine causes the free surface convergence and divergence effect.

  Conclusions  When the submarine depth and stratification mode are the same, the wake field disturbance, wave height and roughness can be reduced when the submarine decelerates, and the acceleration state can significantly increase the probability of near-field disturbances leading to the detection of the submarine.