Cavitation Bubble Interaction with Deformable Structures on a Micron Level

doctoral dissertation

Jure Zevnik (Author), Matevž Dular (Mentor), David Stopar (Co-mentor)

Abstract

Numerous studies have already shown that the process of cavitation can be successfully used for water treatment and eradication of bacteria. However, most of the relevant studies are being conducted on a macro scale, so the understanding of the processes at a fundamental level remains poor. In attempt to further elucidate the process of cavitation-assisted water treatment on a scale of a single bubble, the present thesis numerically addresses interaction between a collapsing microbubble and a nearby structure, that mechanically and structurally resembles a bacterial cell. A fluid-structure interaction methodology is employed, where compressible multiphase flow is considered and the bacterial cell wall is modeled as a multi-layered shell structure. The contribution of two independent dimensionless geometric parameters is investigated, namely the bubble-cell distance δ and their size ratio ϛ. The results show that local stresses arising from bubble-induced loads can exceed poration thresholds of cell membranes and liposomes, and that bacterial cell damage could be explained solely by mechanical effects in absence of thermal and chemical ones. Microstreaming is identified as the primary mechanical mechanism of bacterial cell damage, which in certain cases may be enhanced by the occurrence of shock waves during bubble collapse.

Keywords

bubble dynamics;fluid-structure interaction;

Data

Language:	English
Year of publishing:	2022
Typology:	2.08 - Doctoral Dissertation
Organization:	UL FS - Faculty of Mechanical Engineering
Publisher:	[J. Zevnik]
UDC:	532.528:519.612(043.3)
COBISS:	136130563
Views:	270
Downloads:	67
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	Slovenian
Secondary title:	Cavitation Bubble Interaction with Deformable Structures on a Micron Level
Secondary abstract:	Številne raziskave kažejo, da se lahko proces kavitacije uspešno uporabi v postopkih čiščenja vode in za uničenje bakterij. Vendar se večina relevantnih študij izvaja na makro merilu, zato je razumevanje procesov na temeljni ravni še vedno slabo. Z namenom nadaljnje razjasnitve procesa čiščenja vode s pomočjo kavitacije na nivoju posameznih mehurčkov, dana disertacija numerično obravnava interakcijo med kolapsirajočim mikromehurčkom in bližnjo strukturo, ki je mehansko in strukturno podobna bakterijski celici. Uporabljena je metodologija interakcije fluid-struktura, kjer je upoštevan stisljiv večfazni tok, bakterijska celična stena pa je modelirana kot večplastna lupinasta konstrukcija. Raziskan je vpliv dveh neodvisnih brezdimenzijskih geometrijskih parametrov, in sicer razdalje ? med mehurčkom in celico ter njuno razmerje velikosti ?. Rezultati kažejo, da lahko lokalne napetosti, ki jih vzbudi kolaps mehurčka, presežejo prag poracije celičnih membran in liposomov, ter da je poškodbo bakterijskih celic mogoče razložiti zgolj z mehanskimi učinki, v odsotnosti termičnih in kemičnih mehanizmov. Mikroobtekanje je opredeljeno kot primarni mehanski mehanizem poškodbe bakterijskih celic, ki je lahko v določenih primerih okrepljen ob pojavu udarnih valov med kolapsom mehurčka.
Secondary keywords:	dinamika mehurčkov;interakcija fluid-struktura;računska dinamika tekočin;računska dinamika trdnin;disertacije;Kavitacija;Disertacije;
Type (COBISS):	Doctoral dissertation
Study programme:	0
Embargo end date (OpenAIRE):	1970-01-01
Thesis comment:	Univ. v Ljubljani, Fak. za strojništvo
Pages:	XXVI, 142 str.
ID:	17361119