Three-dimensional full-field simulation of sonic boom emanating from complex geometries over buildings

Abstract

Full-field direct simulation of sonic boom has only been applied to the analysis of axisymmetric geometries. In this work, a more realistic analysis of complex geometries over buildings is achieved by employing a combination of the following four numerical approaches: (i) a hierarchical structured adaptive mesh refinement method, (ii) a ghost fluid method for incorporating the immersed boundary conditions on the solid–fluid interfaces, (iii) a well-balanced finite volume method to allow stable stratification of the atmosphere, and (iv) a segmentation method of the computational domain to increase the efficiency of the computations. The three-dimensional Euler equations with a gravitational source term are solved over a stratified atmosphere. The simulation is split into two stages. Firstly, the entire flow field that involves a delta wing body is solved without buildings. Thereafter, the flow behaviors near the ground are recomputed considering rectangular and L-type buildings. Computational results show that the near- and far-fields waveforms are comparable to those from the wind tunnel experiment and the waveform parameter method, respectively. The waveform shape behind the shock waves is spiked due to the diffracted waves around buildings, with the spiking effect in L-type buildings being stronger than that in rectangular buildings. The pressure rises for rectangular and L-type buildings are significantly amplified due to double and triple reflections, respectively, each with an amplification factor comparable to the theoretical value. These results indicate that full-field simulation is promising for analyzing three-dimensional characteristics of sonic boom emanating from complex geometries passing over buildings.