"During the Nanoshock project, we have developed and improved the versatile advanced multi-resolution computational environment “ALPACA”. This framework is designed for large-scale simulations with novel numerical methods to describe compressible multiphase flows. The use of low-dissipation high-resolution schemes with shock-capturing allows to accurately simulate liquid and gas flows with strong gradients or discontinuities, like present at phase interfaces or at compression shocks. Since November 2020, ALPACA is publically available under open-source license and offers a “state-of-the-art and beyond” tool to the scientific community.
As of flow-physics investigations with ALPACA, we have studied fundamentals of shock-induced bubble collapse dynamics near biomaterial-surrogate gelatin interfaces. This ongoing research helps to understand perforation of living cells, as it occurs e.g. during sonoporation (transient increase of cell permeability with improved drug uptake). Within the last reporting period we have identified a novel flow focusing mechanism that can be technically exploited for non-invasive surgery on cell level or enhanced drug-delivery. Shock-driven interface breakup, surface cleaning, high-viscosity micro-jetting, and liquid-drop explosion phenomena have been investigated with ALPACA revealing an unprecedented level of detail. Results corroborated experimental finding, revealed much of hidden insight, and also falsified erroneous experimental claims. The high quality level of resulting publications demonstrates the value of numerical simulations to the scientific community.
In order to reduce simulation costs of complex flow problems, we have been developing approaches towards the inverse problem. Here, the idea is to understand the sensitivity of the simulation result on the input parameter to define a specific initial setting for a desirable outcome. With these methods, shock-bubble interactions can be manufactured, e.g. to control the peak pressures at a given location in time for complex configurations where explicit numerical simulations would be tedious, if not infeasible.
To reach out to the broader public and to literally visualize our simulation results, we have developed a transformation of flow simulation data to Virtual Reality in collaboration with the Centre for Virtual Reality and Visualization (V2C, LRZ Garching). We can offer now to ""experience"" three-dimensional simulation results, for instance by fly-through of a collapsing helium bubble in air."
