344074 Multiscale Modeling of Two-Phase Flow Through Microtechnology Based Devices With Complex Geometries
Multiscale Modeling of Two-Phase Flow through Microtechnology Based Devices with Complex Geometries
Agnieszka Truszkowska, Frederick Atadana and Goran Jovanovic
Oregon State University, School of Chemical, Biological, and Environmental Engineering, Corvallis, OR 97330, USA
Emails: truszkoa@onid.orst.edu, atadanaf@onid.orst.edu, goran.jovanovic@oregonstate.edu
Bubble management is one of the key challenges in development of many microtechnology-based processes. The presence of a discrete gas phase (bubbles) in a continuous liquid phase flow provides opportunities for advanced design of microtechnology-based devices; but also, causes side effects which alter device performance or even set off device dysfunctionallity. Prevention of entering or generation of gas bubbles in microscale-based devices could be a difficult task; hence, more often effort is shifted towards efficient management of flow of bubbles already present in the system.
In this paper we focus our attention on a two-phase system in which gas phase bubbles may be deliberately introduced to provide (for example): reactants in microreactors, oxygen in bioreactors, or a phase carrier for separation operations. Our work also includes optimization of device architecture, a process based on numerical simulation. Devices with complex micro/nano-features very often enable designs with substantial potential for successful management of a two-phase flow. A 3D simulation of a two-phase flow is computationally intensive, due to a large resolution requirement, which imposes limitations in computational exploration and improvement of device design.
In this paper we propose a novel multiscale modeling approach in describing a two-phase flow with discreet gas phase (bubbles) pertinent for microscale devices with complex structural features. Our effort is focused on the management of bubble motion (velocity, residence time, acceleration), which is influenced by the internal structure of a microscale-based device. We are using a two-dimensional Lattice Boltzmann modeling approach to develop an appropriate forcing function term which acts on bubble interface and effectively accelerates, redirects, or blocks bubble motion. This forcing term serves as an “information carrier” between lower scale with distinct micro-features and upper, geometrically homogeneous scale. The forcing term reflects bubble curvature, contact angles and resulting pressure distribution due to interactions with detailed geometry of the microscale-based device. In the “upper” scale bubble shape is partially transformed but the effective movement of bubbles is preserved from the “lower” scale.
Finally, we demonstrate a possible design optimization approach for microscale devices with microposts. Based on experimentally observed bubble behavior in a liquid flow with force field acting on the bubble interface we numerically produced different gas phase (bubble) retention patterns leading to preliminary conclusions about size and distribution of microscale features in the simulated device.
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