Bionic filters - simulation-based design of additively manufactured porous structures (BiFi)

Project description

Guaranteeing clean air and clean water in a sustainable way is of fundamental importance for the health and quality of life of humans and animals. Filters are usually used to reduce pollutant emissions. The project BiFi aims to develop highly innovative, intelligent filters with optimized bionic structures that are significantly better than the products available on the market in terms of both filters and energy efficiency. The main applications of the project are the removal of microplastics from the wastewater of washing machines and the filtering of particles (e.g. dust, pollen) for interiors.

Project goals

Bionic filter structures through new technology

By combining the latest approaches in flow simulation for topology optimization, rapidly growing computing capacities (high performance computing), new manufacturing options (additive manufacturing) and modern coating techniques, bionic filter structures are designed and manufactured for three key applications. The decisive fluid mechanical processes are strongly dependent on the scale, since fine-scale processes (adherence of dirt particles or droplets on the solid structures of the filter) interact with macro-scale phenomena (volume-averaged description of a complete filter, e.g. to determine the pressure loss) in a complex manner.

Complex intelligence

Through the so-called adjoint optimization, filter structures can be generated which the optimization algorithm optimizes without geometric restrictions with regard to given cost functions (e.g. "minimum pressure loss", "maximum degree of separation"), whose shape can thus be controlled by external influences and whose "intelligence" consists in the fact that they adapt to external conditions in a complex way.

New bionic structures

This achieves optima beyond the results that can usually be achieved with parametric optimizations. The resulting new bionic structures can now be produced for the first time on a filter scale thanks to high-resolution additive manufacturing. It is important to examine and further develop the media compatibility and coatability of the printing materials. The fine structures in the nanometer range are functionalized using modern processes in order to adjust the physical interface properties in the filter-fluid contact area in a targeted manner.

Institute for Flow in Additively Manufactured Porous Media (ISAPS)

The Institute for Flow in Additively Manufactured Porous Structures (ISAPS) was founded in June 2020 at Heilbronn University of Applied Sciences to continue the research work started in BiFi. The institute is located at the interface of the university, cooperation partners and transfer partners and, together with regional and national industrial companies, will deal with applied research questions in the field of porous media, ranging from technical applications (e.g. filters, fuel cells, catalysts, paper and printing technology) medical applications (e.g. brain tumor treatment, patient-specific treatment, SARC-CoV-2 protective masks) to environmental applications (e.g. geothermal energy, underground CO2 storage) range. Several high-performance PCs and test stands are available to ISAPS for this purpose, and there is also access to the bwUniCluster2 as the high-performance infrastructure of the state of Baden-Württemberg. The acquisition of a high-resolution µCT scanner is in preparation for the analysis of the additively manufactured structures. An annual symposium, a series of seminars on “Porous Structures” and an ISAPS workshop are intended to provide a platform for exchange and offers for internal and external further training. An industrial advisory board, consisting of representatives from industry

Workflow (showcase structure and optimization goal)

BiFi workflow from flow simulation and geometry optimization to additive manufacturing and plasma coating of filters to comparison with experiments and transfer to practice.

Bifi Workflow

First, the flow through an original geometry (here exemplary: cylindrical structure) is simulated and the actual value of the aerodynamics is determined.

In the optimization step, the optimization goal is formulated (here exemplary: minimum drag coefficient) and the geometry is deformed towards the optimization goal in a morphing step. In just 4 steps, the drag coefficient could be reduced by 8.5%.

The optimized geometry looks bionic and can also be manufactured thanks to additive manufacturing.

The project is funded by the Carl-Zeiss Foundation (Carl-Zeiss-Stiftung).

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