# Research on a Strategy for Prediction Methods of Submarine Self-Propulsion Hydrodynamic Performance
## 1 Introduction
[17] used the steady-state Moving Reference Frame (MRF) method for numerical simulations, estimating propeller rotational speeds with assumed thrust deduction factors and adjusting rotational speeds based on the difference between calculated and set forces to obtain the propeller's rotational speed at the self-propulsion point. [PERSON] [18] used computational fluid dynamics (CFD) methods for self-propulsion simulation analyses, initially determining the self-propulsion point based on empirical thrust deduction coefficients and the propeller's open-water performance curves. They employed a submarine with a propeller calculation strategy for unsteady hydrodynamic RANS simulations, comparing submarine resistance and propeller thrust at three propeller rotational speeds to determine the self-propulsion point's propeller rotational speed. [PERSON] et al. [19; 20] used RANS methods to study self-propulsion hydrodynamic  
Figure 1: Sketch of a nuclear submarine [1]. performance using both body force and submarine-propeller calculations, with the latter employing the steady MRF method. Their research validated the applicability of RANS methods for underwater vehicle self-propulsion predictions, showing that body force estimates yielded lower propulsion efficiency and higher output power. [PERSON] et al. [21] used the RANS method, initially employing the steady MRF method, followed by the unsteady Rigid Body Motion (RBM) to extract the unsteady force of the propeller, studying propeller excitation mechanisms in self-propulsion states with and without appendages, X-tail rudders, and single-hull bodies, though they did not detail the method for determining the self-propulsion point. [PERSON] et al. [22] conducted numerical simulation research on the self-propulsion state of a submarine using the MRF method and virtual disk method. The results showed that a virtual disk numerical model can be applied in self-propulsion simulations that only require the open-water propeller performance as an input. For the SUBOFF submarine model with KP505 propellers, [PERSON] et al. [23] used an overlapping grid and RBM method to study the hydrodynamic performance near ice ridges, finding that ice ridges reduced the propeller rotational speed at the self-propulsion point by about 11%. [PERSON] [24] used the RANS method and Volume of Fluid (VOF) model with sliding mesh to simulate the submarine's performance at different velocities and depths, with and without a free surface. These studies used a submarine with propeller calculation strategy, determining the self-propulsion point's propeller rotational speed by adjusting three sets of propeller rotational speeds. In summary, researchers have used the steady-state Moving Reference Frame (MRF) method and the unsteady Rigid Body Motion (RBM) method for numerical simulations of submarine self-propulsion hydrodynamic performance. MRF stands for Moving Reference Frame method, a method that simplifies the problem of propeller rotation by introducing a relative motion reference frame. It is a steady-state method known for its stability and ease of convergence. RBM refers to Rigid Body Motion, also known as the Sliding Mesh Method. This transient method simulates the actual motion of the propeller by rotating the mesh, with flow field information transferred across the interface between the rotating domain and the external stationary domain. While it is recognized that the MRF method is significantly more efficient than the RBM method in CFD simulations, the differences in calculation accuracy and efficiency between the two methods have not been clearly defined. Additionally, various calculation strategies in submarine self-propulsion hydrodynamic performance simulations have not been thoroughly discussed.