| Description |
Speaker: Aswin Gnanaskandan
Title: Multiscale modeling of hydrodynamic and acoustic cavitation
Abstract: Cavitation refers to formation, growth and collapse of vapor/gas bubbles in a liquid due to the local pressure dropping below a threshold pressure. Cavitation plays an important role in aerospace, marine and biomedical applications with both beneficial (e.g. thermal ablation, lithotripsy) and detrimental effects (e.g. erosion, loss of efficiency). The ability to accurately predict cavitating flow behavior is imperative to control its formation, exploit its benefits and reduce its detrimental effects. A major difficulty in accurately predicting cavitating flows lies in the complex multiple length scale nature of such flows. Applying a universal model to cater to all the length scales is prohibitive in terms of computational cost. Hence, the most practical way to solve the multiscale problem is to develop models separately at both micro and macro length scales and then develop appropriate bridging models that can transition smoothly between models at different length scales. In this talk, I will be discussing two multiscale problems, one in hydrodynamic cavitation and another in acoustic cavitation with applications in navy and biomedicine.
In the first study, we are interested in studying sheet to cloud cavitation, a hydrodynamic phenomenon prevalent in marine propellers and usually detrimental to the structural integrity of the propeller. To address the multiscale aspect of this phenomenon, a model that can both resolve large scale cavitation bubbles on the grid and represent unresolved subgrid bubbles will be presented. A transition algorithm to manage the mass and momentum transfer between the two frameworks will be demonstrated with validation studies. Finally, the application of this model to study sheet to cloud cavitation will be presented.
In the second study, we aim to understand the response of gaseous microbubbles to an imposed acoustic field and the resulting dynamics which can be harnessed beneficially in biomedical applications. In particular, we are interested in studying the ‘acoustic to thermal energy conversion mechanisms’ when acoustically cavitating microbubbles are subject to a high frequency acoustic field. A multiscale model that can resolve the acoustic field and simultaneously model the response of a cloud of microbubbles will be presented along with validation results compared with in vitro experiments.
About the Speaker: Dr. Aswin Gnanaskandan is an Assistant Professor in the Department of Mechanical & Materials Engineering, Worcester Polytechnic Institute (WPI). He graduated with PhD (2015) in Aerospace Engineering and Mechanics from the University of Minnesota, where he was the recipient of the “John and Jane Dunning Copper” fellowship. During his PhD, he worked on numerical modeling of multiphase cavitating flows and developed a low dissipative, massively parallel, unstructured methodology to simulate multiphase flows. Subsequently he moved to California Institute of Technology as a post-doctoral researcher where he worked on physical and subgrid scale modeling of high-pressure multispecies flows for which he received a “NASA certificate of recognition” in 2018. Prior to joining the faculty at WPI in Fall 2020, he was a Research Scientist at Dynaflow Inc., where he worked on developing numerical models for multiphase flows for applications in aerospace engineering, marine engineering, and biomedicine. At WPI, his research mainly focuses on developing high-fidelity mathematical models for multiphase flows and leveraging their applications to answer critical questions in engineering and biomedicine. His research is currently supported by NSF, ONR and Center for Advanced Research in Drying. |
