Research on acoustic propagation in multiple fluids has important application values in naval architecture and ocean engineering, such as sound propagation in pipelines filled with water and air, and the detection of buried objects. There are two difficulties in solving such problems with the use of the classical finite element method: one is the serious numerical dispersion error in the finite element solutions under medium and high wave numbers; the other is the need to use refined mesh grids to discretize the fluids near the coupling interface. These difficulties lead to a large computational cost for the finite element method, and the manual intervention to generate refined grids. Compared with the finite element method, the weak-form meshfree method does not require traditional grids, and the dispersion error effect in its solution is much weaker, ensuring good computational accuracy and efficiency. However, the meshfree shape functions are usually discontinuous in the problem domain, resulting in the inability of the continuity condition of the acoustic particle velocity to be naturally satisfied on the interface. Therefore, this paper uses the penalty function method to reconstruct the continuity condition of the acoustic particle velocity on the interface, and proposes a Galerkin weak form suitable for meshfree methods for sound propagation in multiple fluids. Numerical analysis shows that the meshfree solutions is consistent with the reference solutions, and the computational accuracy and efficiency of the meshfree method can be higher than the finite element solutions.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |