Three-dimensional Bullets Research Articles

Dual Mesh Technique for Hydroacoustic Prediction of Cavitating Flows around a Three-Dimensional Bullet

Nowadays, hydroacoustics is of great importance. A major source of underwater noise is cavitation noise. One of the difficulties in cavitation noise prediction is its complex formation mechanism. In this paper, a cavitating bullet is taken as the research object, and detailed numerical simulation research of the local cavitation for this three-dimensional model is carried out. Ffowcs Williams and Hawkings equation (FW-H) is adopted. The quadrupole term is obtained by the direct volume integration method. Furthermore, dual mesh technique is adopted to achieve fast calculation. The results show that the dual mesh technology reduces the computational complexity of the nonlinear sound pressure significantly. With the appropriate acoustic grid size, the dual mesh method can ensure the same accuracy as the CFD grid. This provides a reliable way for the calculation of nonlinear sound pressure in the cavitation phenomenon.

Theoretical Analysis of Airy-Gauss Bullets Obtained by Means of High Aperture Binary Micro Zonal Plate.

We theoretically analyze the methodology for obtaining vectorial three-dimensional bullets, concretely Airy–Gauss bullets. To do this, binary micro zonal plates (BZP) were designed in order to obtain different Airy–Gauss bullets with sub-diffraction main lobe width. Following the vectorial diffraction theory, among the electrical field, we extend the theory to the magnetic field, and thus we analyze several properties such as the Poynting vector and the energy of Airy–Gauss vectorial bullets generated by illuminating the designed BZP with a temporal Gaussian circular polarized pulses.

三维枪弹痕点云数据处理及特征提取研究

三维枪弹痕点云数据处理及特征提取研究

Light bullets in nonlinear periodically curved waveguide arrays

We predict that stable mobile spatiotemporal solitons can exist in arrays of periodically curved optical waveguides. We find two-dimensional light bullets in planar arrays with harmonic waveguide bending and three-dimensional bullets in square lattices with helical waveguide bending using variational formalism. Stability of the light-bullet solutions is confirmed by the direct numerical simulations which show that the light bullets can freely move across the curved arrays. This mobility property is a distinguishing characteristic compared to previously considered discrete light bullets which were trapped to a specific lattice site. These results suggest new possibilities for flexible spatiotemporal manipulation of optical pulses in photonic lattices.