| The study of electromagnetic scattering characteristics of wakes generated by ships on the sea surface has always been a hot topic for scholars at home and abroad.It plays an important role in the identification of sea surface target,marine environmental monitoring and national defense military activities.With the development of stealth technology,direct detection of moving ships on the sea surface becomes more and more difficult.However,wakes generated by the ship exist for a long time and cannot be eliminated.Therefore,it is an important way to detect the ship by studying the wake of the ship to obtain the specific parameters such as the size,heading and speed of the ship.There are four main wakes generated by the ship,namely Kelvin wake,turbulent wake,internal wave wake and narrow V wake.Due to differences in geometric models,the simulation methods used for researching different types of wakes generated by the ship will vary.By analyzing the electromagnetic scattering characteristics of different types of wakes generated by the ship,it can provide technical support for the detection and tracking of ship targets on the sea surface.With the rapid development of computer technology,in order to improve the efficiency of electromagnetic scattering calculation and the utilization computer resources,it is particularly important to perform parallel acceleration processing on the program when performing electromagnetic scattering calculation on the wake generated by the ship.The small slope approximation method is very time consuming to calculate the electromagnetic scattering of the wake under the condition of large frequency band and the large region.By using the parallel acceleration technology,multiple processes or threads can be started to perform calculation,thereby improving the calculation efficiency.The main work of this paper is as follows:1.Several typical sea-spectrum models are analyzed,such as PM spectrum,A.K.Fung spectrum and Elfouhaily spectrum.The Monte Carlo method is used to simulate the generation of two-dimensional rough sea surface,and the sea surface under different wind speed and wind direction is compared and analyzed.Then the Kelvin wake model is established and combined with the sea surface model to obtain the geometric model of the Kelvin wake with the sea surface under different parameters.2.The theory of small slope approximation method is introduced,and the cone wave is introduced into the small slope approximation model to avoid the edge truncation effect at the end of the rough surface.The first-order and second-order small-slope approximation calculation results of cone wave incidence are compared.The electromagnetic scattering characteristics of electrical large size sea surface and the fully polarized electromagnetic scattering characteristics of sea surface with Kelvin wake generated by the moving ship are studied.3.Based on the theory of hydromechanics and CFD software,the turbulent wake generated by the moving ship is studied.Firstly,the turbulent wake contour model is established by using empirical formulas.Then the turbulence model is realized by CFD software and the turbulent flow field is analyzed.Finally,based on the established turbulent wake model,the electromagnetic scattering characteristics of turbulence wake are studied.4.Applying the fast-developing computer parallel technology,namely MPI parallel technology and OpenMP parallel technology to accelerate the programs of calculating electromagnetic scattering of Kelvin wake in this paper.The parallel processing reduced the simulation time and improved the calculation efficiency,so as to meet the electromagnetic simulation requirements of electrical large size wakes generated by the ship.At the same time,it provides technical support for detecting and tracking of ships in complex marine environments. |
PDF Full Text Request