# Numerical Analysis on Self-Propulsion of a Waterjet-Propelled Ship with Different Propulsion Models
###### Abstract  
The hydrodynamics of the waterjet-propelled ship is a challenging issue due to the sophistication of waterjet system geometry as well as waterjet-hull interaction. In current study, three different propulsion models, namely, multiple reference frame (MRF) model, sliding mesh model and body-force model, are utilized to simulate the self-propulsion of a waterjet-propelled ship model. A body-force model based on a User-Defined Function (UDF) on the ANSYS Fluent platform is proposed. The computational cost, wave pattern, jet stream surface, and self-propelled hull resistance of the MRF model and body-force model are compared. Comprehensive comparisons of the internal ingested flow field of the control volume are made, especially at the capture area and nozzle section, with the two different models. In addition, the resistance increment fraction and jet system thrust deduction fraction with the two different models are investigated. Lastly, the flow field with the steady MRF model, the body-force model (RANS) and the transient sliding mesh model (URANS) are compared. waterjet; self-propulsion; multiple reference frame model; sliding mesh model; body-force model +
Footnote †: journal: Applied sciences  
Computational Fluid Dynamics (CFD) techniques make it more effective and efficient to investigate the waterjet-hull interaction, especially in recent years. [PERSON] et al. [PERSON] et al. (2018) analyzed the waterjet pump characteristics for a Joint High Speed Seallift (JHSS) hull by RANS computations, and mentioned the momentum non-uniformity factor. [PERSON] et al. [PERSON] et al. (2018) derived an integral force/moment waterjet model to predict the ship local flow variables by CFDSHIP-IOWA solver. [PERSON] et al. [PERSON] et al. (2018) applied the unsteady Reynolds-Averaged Navier-Stokes (URANS) CFDSHIP-IOWA solver to simulate the flow field of a bare hull and the self-propelled conditions. [PERSON] et al. [PERSON] et al. (2018) presented a fast and robust method, called the pressure jump method, to simulate the waterjet-hull interaction with potential flow theory. The main parameters affecting the waterjet-hull interaction were also determined in his doctoral thesis [PERSON] et al. (2018). Furthermore, [PERSON] et al. [PERSON] et al. (2018) employed numerical simulations to study the relation between net thrust and gross thrust. They used CFD to address the large variation of water thrust deduction with Froude number [PERSON] et al. (2018). The impact on the external flow field could further affect the momentum velocity coefficient, which was an important evaluation index of the waterjet-hull interaction [PERSON] and [PERSON] [PERSON] and [PERSON] (2018). [PERSON] and [PERSON] [PERSON] and [PERSON] (2018) found that the non-uniform inflow reduced the external characteristics of the waterjet pump and led to the huge fluctuation of energy performance with time. [PERSON] et al. [PERSON] et al. (2018) adjusted the impeller rotational speed to balance the horizontal force of the waterjet-propelled trimaran, and then determined the self-propulsion point. [PERSON] et al. [PERSON] et al. (2018) studied the effect of improving the blade tip size in pump-jet propulsor through CFD numerical simulation. [PERSON] and [PERSON] [PERSON] and [PERSON] (2018) studied the hull-waterjet interaction of a planning trimaran, including analysis of thrust deduction and interaction efficiency. They also conducted detailed investigations on the respective effect of waterjet suction and jet action on hull resistance with Froude Number, as well as the effect of hull displacement on the hydrodynamics for the same planning trimaran ([PERSON] et al., 2018; [PERSON] et al., 2018). [PERSON] et al. [PERSON] et al. (2018) investigated the stabilizer fin's influence on the flow fields of a waterjet-propelled ship, including the boundary layer distribution around the hull and the momentum velocity coefficient at station 1a.