The research unit will tackle the issue of lacking fundamentals for oil-refrigerant multiphase flows in gaps with moving boundaries. Experts from fluid mechanics (project area A) and thermophysical property research (project area B) will team up to provide a validated calculation model for multiphase surge and gap flows of such strongly asymmetric mixtures in rotary positive displacement compressors (RPDC) for the first time. The state-of-the-art of methods for simplified simulation of these types of flow in RPDC (A1), the fundamental knowledge in the fields of optical flow measurements (A2) and high-resolution numerical gas-liquid flow simulations (A3) as well as the accurate measurement (B1, B3) and modeling (B2, B4) of thermophysical properties of strongly asymmetric mixtures will be advanced. Subproject A2 at ISTM aims at providing experimentally obtained information on the considered multiphase gap flows. For this purpose, various promising measurement strategies are combined and enhanced so as to develop a novel laser-optical high-speed imaging framework. This set of measurement techniques includes defocusing particle tracking velocimetry (DPTV), interferometric particle imaging (IPI) and high-speed imaging (HSI). The content and images have been sourced from https://www.for-archimedes.de. Further information about the project can be found on the aforementioned website.