Sh Rezaei, M Eskandari-Ghadi, M. Rahimian,
Volume 36, Issue 1 (9-2017)
Abstract
The acoustic wave velocity depends on elasticity and density at most materials, but because of anisotropy and especially piezoelectric coupling effect, the acoustic wave propagation at piezoelectric based crystalloacoustic materials, is an applied and challenging problem. In this paper, using modified Christoffel's equation based on group velocity concept, the effect of anisotropy and piezoelectric coupling at different wafers of lithium niobate crystalloacoustic (strong anisotropy) on acoustic wave velocity (semi-longitudinal, semi-vertical transverse wave and semi-horizontal transverse wave) is investigated, and validated by experimental data. Then, the acoustic wave velocity ranges that can be supported are determined. The result of this study can be essential at acoustic metamaterials design, Phononic crystal and piezoelectric based wave-guides.
F. Shabani, M. Saghafian, D. Saeidi, F. F. Momennasab ,
Volume 39, Issue 2 (2-2021)
Abstract
Particulate separation has many applications in medicine, biology and industry. In this research, the separation of polystyrene particles with a diameter of 10, 20 and 30 μm in the fluid flow of a microchannel is investigated. The microchannel consists of a spiral region and a straight region under the influence of acoustic waves. In the spiral region, the particles under hydrodynamic effects undergo the initial separation; then the particles enter the straight region of the microchannel, and the final separation of the particles is done by the force generated and exerted through the acoustic waves. The effects of acoustic frequency and the number of spiral region loops on separation are investigated. The results show that for measured dimensions and parameters, at 1 MHz acoustic wave, when the number of loops is 2 for the spiral region, the particles at the end of the path are in a suitable position for separation. In addition, the results show that the separation of particles with this hybrid system is better than that done by the simple methods, and the separation rate can be as high as 100%
