Rapid Simulation for Passive Millimeter-Wave Imaging of Large-Scale Kelvin Wake Using Wave Height and Brightness Temperature Similarity

Ship wakes have special millimeter-wave radiation characteristics, which are of great significance for the indirect monitoring technology of sea surface ships based on passive millimeter-wave (PMMW) imaging. Due to the complex wave height distribution and huge coverage area, the millimeter-wave radiation propagation modeling and simulation of the ship wake face challenges. Generally, the computational fluid dynamics (CFD) simulation and brightness temperature (TB) ray tracing of the full-size model require a large amount of computation, which makes it difficult to analyze the model quickly. In this paper, a rapid simulation method for PMMW imaging of large-scale Kelvin wake is proposed by establishing the wave height similarity relation and the TB similarity relation. The relation of wave height similarity is derived using the mathematical method, and the constraints are provided from the perspective of the Froude number. A large ship can be considered analogous to a smaller ship, and the CFD method is employed to determine the distribution of Kelvin wake wave height for a small ship. Subsequently, utilizing the atmospheric radiation transmission model in conjunction with the TB data obtained from the Kelvin wake of the small ship, a simulation of the PMMW imaging for the Kelvin wake of the large ship is conducted. Simulation experiments involving Wigley and KCS ship models demonstrate that the proposed rapid simulation method can substantially decrease the number of model elements, reduce computational complexity, and shorten simulation duration, all while preserving the high accuracy of PMMW imaging simulations. Furthermore, the proposed method can incorporate various environmental complexities such as different sea conditions, weather conditions, and seasonal variations into the equivalent simulation.