# Research on the Hydrodynamic Performance of a Pentamaran in Calm Water and Regular Waves
## 1 Introduction
[25] investigated the resistance performance of a pentamaran with different outrigger inclination angles. The results showed that the influence of the front outrigger inclination angle change on the resistance of the pentamaran had a certain rule, and the resistance of the pentamaran could be reduced by adjusting the front outrigger inclination angle. Most of the above research was carried out via experiments, and some of them were carried out through numerical simulations. The biggest advantage of experimental research is to provide reliable data for subsequent research to replicate. Ship model tests are commonly used to analyze the hydrodynamic performance of ships. The accuracy of ship model tests has also been widely recognized by the engineering community. However, the disadvantages of ship model tests are also obvious: time-consuming nature and high economic costs. The data that can be measured each time are very limited, and during the test process, uncertain factors such as scale effects and test equipment accuracy can bring many test errors that need to be corrected. CFD is a numerical simulation method that  
Figure 1: The concept design of a pentamaran [7]. considers the effect of fluid viscosity [26; 27; 28; 29]. With the continuous improvement of CFD, the application of CFD in ship hydrodynamics is becoming increasingly more common [30; 31; 32; 33; 34; 35; 36; 37]. [PERSON] et al. [38], for example, used the finite volume method to numerically simulate the flow field around a Series60 ship in the range of medium and low speeds. [PERSON] et al. [39] studied the additional resistance of three different bows of KVLCC2 in short waves using CFD. [PERSON] et al. [40] combined the optimization algorithm and CFD to optimize the bow of a 1300 TEU container ship and realized the optimal design of drag reduction for this ship type. [PERSON] et al. [41] used the open source CFD software OpenFOAM to numerically predict the hydrostatic resistance of two fishing boats. [PERSON] et al. [42] used a 66 KDWT bulk carrier as the parent ship and calculated the resistance characteristics of the pointed bow and the blunt bow in calm water and waves using CFD. [PERSON] et al. [43] predicted the wave induced force of irregular waves on slender ships on the basis of CFD and found that the CFD results were in good agreement with the experimental fluid dynamics (EFD) results through comparison. [PERSON] et al. [44] used the CFD method to directly simulate the zigzag maneuver of KCS in shallow water, finding that they can better predict the parameters such as force and torque. According to the literature, on the basis of viscous flow theory, the CFD method has the advantages of short cycle and low cost, which cannot be replaced by ship model experiments. The simulation results can also achieve high calculation accuracy. This paper aims at investigating the hydrodynamic performance of the pentamaran in calm water and regular waves. According to the literature, the hydrodynamic performance of the pentamaran has been discussed and verified. However, most of the research on the performance of the pentamaran was conducted in calm water. There are few reports on hydrodynamic performance of the pentamaran in waves. In most cases, ships do not sail in calm water, but in waves. Therefore, the study of the hydrodynamic performance of a pentamaran in waves is helpful for its hydrodynamic design, thereby playing a positive role in the shipping industry and in environmental protection. On the basis of the CFD method, the dynamic fluid body interaction module and the overset mesh were used to simulate the motion response of the pentamaran. The simulation results were also compared with those of the monohull in order to explore the changes in the resistance components and reveal the drag reduction mechanism of the pentamaran during high-speed sailing.