Numerical Analysis of Sound Generation of Insect Flapping Wings

概要

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Insect flapping sound is a consequence of flow disturbance generated by flapping wing motion; spatial and temporal changes of pressures on wing surface and vortex structures generated by wing motion are considerable sources of flapping sound. To uncover such sound generation mechanisms in flapping wings, we have developed a hybrid method combining CFD techniques and acoustic analysis. Unsteady flows around a hovering insect 'flying' with realistic wing kinematics are computed with a multi-blocked, overset grid NS solver. Acoustic analyses of monopole and dipole sound sources are undertaken using Ffowcs-Williams and Hawkings (FW-H) method. Numerical analyses are carried out for three typical insects (hawkmoth, honeybee, and fruitfly). CFD analysis offers detailed vortex aspects and induced pressure distributions on the wing surfaces showing concrete evidence of sound sources; acoustic analysis clarifies characteristics of the induced flapping sounds, including sound direction and its spectrum distributions.
日本学術会議「機械工学委員会・土木工学・建築学委員会合同IUTAM分科会」の論文