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The exploitation of wave energy will benefit remote islands considering environmental, social, and economic aspects. Located more than 250 kilometres off the Hainan Island, Xisha Islands is an archipelago in the South China Sea (SCS) that is yet to be grid-connected. Previous studies suggested the SCS has vast and untapped wave energy. Here, high-resolution wave hindcast generated by a nesting SWAN model is used for the assessment of wave energy resource in Xisha Islands. The result of the spatial-temporal analysis highlights the seasonal variability in wave energy, as the mean wave power density ranging from 2 to 12 kW/m between summer and winter. Spatial variation of wave energy majorly caused by depth-induced wave breaking, and blockage effect of islands and reefs. Available wave conditions for the operation of WECs are also discussed, showing that wave energy can provide stable and sustainable energy to islands in Xisha.

Two numerical wake model were established, one based on full geometry turbine and one based on actuator disc theory. The Actuator disc momentum theory assumes turbine as a constant sink of momentum in numerical domain. Results of numerical models were compared with experimental results, the experimental data is in good agreement with the simulation data. The difference between two models were analyzed in detail. The the difference between simulation results of actuator disc and test results are slightly larger in near wake region, the difference gradually decreased as the axial distance increased. The lack of the simulation of rotation of the model may lead this difference. The effect to wake recovery of blockage ratio was studied using numerical model based on actuator disc theory, 11 cases were studied, the results showed that the blockage ratio can heavily effect the recovery speed of turbine wake. Along the centerline, the degree of wake recovery decreased as the blockage ratio increased before X/D=10.8, and the degree of wake recovery increased as the blockage ratio increased after X/D=10.8.