As a coastal trading city in China, Shantou has complex terrain and changeable sea conditions in its coastal waters. In order to better protect the coastal engineering and social property along the coast, based on the numerical simulation method, this paper constructed a detailed hydrodynamic model of the Shantou sea area, and the measured tide elevation and tidal current were used to verify the accuracy of the model. Based on the simulation results, the tide elevation and current in the study area were analyzed, including the flood and ebb tides of astronomical spring tide, the flood and ebb tides of astronomical neap tide, the high tide, and the low tide. In order to find the main tidal constituent types in this sea, the influence of different tidal constituents on tide elevation and tidal current in the study area was analyzed. At the same time, the storm surge model of the study area was constructed, and the flow field under Typhoon “Mangkhut” in the study area was simulated by using the real recorded data. Typhoon wind fields with different recurrence periods and intensities were constructed to simulate the change in the flow field, the sea water level, and the disaster situation along the coast. The results showed that under normal sea conditions, the sea water flows from southwest to northeast at flood tide and the flow direction is opposite at ebb tide. The tidal range is large in the northwest and small in the southeast of the study area. The tides in the study area are mainly controlled by M2, S2, K1, and O1 tidal constituents, but N2, K2, P1, and Q1 tidal constituents have significant effects on the high water level. The water level caused by typhoons increases significantly along the coast of Shantou City. In the west area of the Rong River estuary, a typhoon with a lower central pressure than 910 hPa may induce a water increase of more than 2 m.

Submarine Pipeline End Manifold (PLEM) is the converge end or termination of submarine pipelines, which is used to provide additional support for equipment in the submarine production system on the seafloor. However, PLEM is vulnerable to extreme waves (i.e., tsunami waves). In this study, a two-phase flow model is developed with the finite volume method for simulating the tsunami-like wave impinging on the PLEM. Depending on the real-world tsunami wave recorded in 2011 tsunami event, a tsunami-like wave is generated numerically depending on N-waves theory. In order to ensure the accuracy of the calculation, this model is verified against some theoretical and experimental studies firstly. Then, the hydrodynamic characteristics and forces on the PLEMs under the different tsunami-like waves are investigated systematically. Due to the flow causes strong disturbance to different parts of the PLEMs, the Fast Fourier Transform (FFT) method is adopted to analyze the irregular hydrodynamic force signals for better to understand the characteristics of forces in the frequency domain. In the simulations, different environmental and PLEM structural variables are considered, such as wave height, pipe distance, and PLEM bottom seat length. The hydrodynamic characteristics under different tsunami-like waves passing the various submarine PLEMs are discussed, which indicates that the vortex field evolutions and hydrodynamic forces under different waves on the PLEM are significantly different.