| Autor: |
Hisayoshi MURASAWA, Ryotaro KAMEDA, Hiroyuki TAKAHIRA |
| Jazyk: |
angličtina |
| Rok vydání: |
2024 |
| Předmět: |
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| Zdroj: |
Journal of Fluid Science and Technology, Vol 19, Iss 2, Pp JFST0012-JFST0012 (2024) |
| Druh dokumentu: |
article |
| ISSN: |
1880-5558 |
| DOI: |
10.1299/jfst.2024jfst0012 |
| Popis: |
The interaction between bubbles and tissues (bone and fat) in ultrasound and the mechanism of drug transport accompanied by bubble collapse were investigated numerically by using the ghost fluid methods with zonal grids. A parameter defined by the ratio of t0 to ts which is proportional to the ratio of bubble radius to wavelength, where t0 is the bubble collapse time and ts is the period of an incident pressure wave, was used to characterize the relationship between the incident pressure waveform and the bubble collapse. It was found that the bubble collapse near a tissue surface was classified into three types by considering the penetration of liquid jet and bubble blobs into the tissues. The transport process of matter (imaginary drug) distributed around the bubble surface was calculated with the bubble collapse. The results showed that the mechanism of matter transport due to bubble collapse was summarized as follows. First, both the shock wave by the liquid jet impact on the bubble surface and the rebound shock wave lead to the depression of the tissue wall, and the matter is transported with the vortex flow due to liquid jet formation. Then, the bubble penetrates into the depression, increasing the amount of matter transported into the tissue. The bubble collapse and the matter transport in the bone wall case were compared with those in the fat wall case. Although the maximum wall pressure was higher in the bone case, the amount of matter transported inside the tissue was higher in the fat case. This was caused by the difference in the acoustic impedance between both tissues: the large acoustic impedance of bone induced the reflection of the incident wave, leading to the superposition of the incident wave and the reflection wave that contributed to the acceleration of bubble collapse. Since the stiffer property of bone suppressed the development of the vortex flow and the bubble growth inside the tissue, a larger circulation existed inside the fat, which contributed to the advection of the matter, resulting in a higher concentration of matter inside the fat than inside the bone. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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