中文摘要：

针对经典边界元方法对掠入射角度下的散射估计精度较低的问题，发展了一种边界无网格模型。此模型将散射体视为具有无限延伸的形式，避免了经典边界元法中薄板形式所导致的声压差问题，而且更加符合实际房间中散射体的存在形式；模型利用无网格算法实现数值仿真，可对任意表面形状特别是曲面散射体具有更高的仿真精度。利用边界无网格模型计算了不同形状散射体的散射系数及散射声场，并将结果与解析方法、测量实验进行了对比。对比结果表明，边界无网格模型可以准确预测散射体的散射性质，特别是对掠入射角度的估计要优于经典边界元法。研究结论可应用于室内声学散射体特征预测及优化设计，对提高声场扩散及室内音质水平具有重要意义。

英文摘要：

The Boundary Element Method is a classical method to numerically evaluate the scattering property. How- ever, its accuracy usually degenerates when sound waves impinge on diffusers in an grazing angle. In order to improve the simulating accuracy for grazing incident waves, a Boundary Meshless Model which is applicable to diffusers with arbitrarily shaped surfaces is proposed. In the model, diffusers are assumed to be attached on infinitely extent walls, which avoids the problem of the sound pressure difference caused by the form of thin plate in traditional Boundary Element Method. The meshless method is used to implement numerical calculations, which contributes that the model is applicable to diffusers with rough surfaces, especially curved surfaces. The Boundary Meshless Model is then used to analyze the scattering property of diffusers in numerical verifications. Comparisons of results with those obtained by the analytical method and measurement have proved that the model has higher accuracy than the Boundary Element Method on evaluating the scattering property for grazing incident angles. The method can be used to design the sound diffusers in architectures to promote diffusions and present echoes. It is potentially effective to improve the sound quality of the room.