A method for reconstructing the free-field acoustic characteristics of an underwater target based on higher-order elements

Obtaining free-field characteristics in noisy environments is essential for noise control and stealth evaluation. To address this challenge, the sound field recovery technique based on the Boundary Element Method (BEM) offers a robust solution. Traditional BEM typically employs linear elements, leading to high computational costs and geometric errors for complex structures, particularly within the medium-to-high frequency range. To address this issue, we combined the high-order quadratic element BEM with the sound field recovery method to establish an improved method. This method separates the radiated and incident fields based on nodal pressure and velocity on the measurement surface, thereby eliminating scattering and reconstructing free-field characteristics. Validated by the BeTSSi benchmark model, demonstrating that, compared to linear methods, errors are significantly reduced and the effective computational frequency band is notably broadened. This confirms the enhanced efficiency and accuracy of the method for large-scale targets, offering a reliable approach for the in-situ acoustic measurement and evaluation of complex underwater vehicles.