In the fluid-structure interaction analysis, the finite element formulation is performed for the wave equation for dynamic fluid pressure, and the dynamic pressure is defined as a degree of freedom at the fluid nodes. Therefore, to connect the fluid to the structure, it is necessary to connect the degree of freedom of fluid dynamic pressure and the degree of freedom of structure displacement through an interface element derived from the relationship between dynamic pressure and displacement. The previously proposed fluid-structure interface elements use conformal finite element meshes in which the fluid and structure match. However, it is challenging to construct conformal meshes when complex models, such as water purification plants and wastewater treatment facilities, are models. Therefore, to increase modeling convenience, a method is required to model the fluid and structure domains by independent finite element meshes and then connect them. In this study, two fluid-structure interface elements, one based on constraints and the other based on the integration of nonsmooth functions, are proposed in nonconformal finite element meshes for structures and fluids, and their accuracy is verified.

Five species of the subfamily Cicadinae are found in urban areas at the center of the Korean peninsula, including Cryptotympana atrata, Hyalessa fuscata, Meimuna mongolica, Meimuna opalifera and Graptopsaltria nigrofuscata. Out of those species, the densities of C. atrata and H. fuscata are generally high in the urban area. I hypothesized that there is a vigorous acoustic interaction where two species are abundant. We tested this hypothesis by conducting the 24-h recording experiments in four localities: Gwacheon(GC), Jamsil(JS), Ewha University(EU) and Yangpyeong(YP). Based on the preliminary enumeration surveys of exuviae, GC and JS were designated as high density localities and EU and JS were as low density localities. The results of 24-h recordings and abiotic factor based on the multinomial logistic regression showed that C. atrata and H. fuscata were negatively correlated in high density area GC and JS. In JS and EU, the density of H. fuscata is close to each other. However, the probability of chorusing in JS is significantly lower than EU. This might be due to acoustic competition between two species. Moreover, we confirmed that the choruses of males of C. atrata produced loud choruses usually during the day when temperature high and males of H. fuscata produced calling song throughout the day but peaked in the morning and night. Consequently, multi-species cicada in different temporal pattern probably cannot be explained by only acoustic interaction but the combination of both abiotic and biotic factors probably constrain multi-species cicada to call together during the limited time windows.