Investigation of stability and drop-off in thin liquid films on inclined fibers

• Applicant: Professor Dr.-Ing. Reinhold Kneer
• Subject Area: Chemical and Thermal Process Engineering ; Energy Process Engineering
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 541089365

Falling liquid film flows are found in many technical applications as they offer an increased surface area and thus promote heat and mass transfer processes. However, when the film flows on the underside of a substrate or along an inclined cylinder, dripping can occur, which may be undesirable or beneficial, depending on the application. For example, preventing dripping ensures a uniform coating process in technical applications, or offers the possibility of collecting water during fog harvesting in dry regions in a less technical environment. Existing research has extensively studied film flows on inclined or vertical planar substrates and vertical cylinders, but there is a lack of experimental and numerical data on film flows on inclined cylinders. There is also no theoretical analysis of film flows on inclined thin cylinders (objects with large surface curvature, e.g., fibers), which is complicated by the nonlinear and asymmetric nature of the problem. Hence, this project aims to comprehensively characterize the dripping mechanisms, identified in the previous project, in suspended film flows on inclined fibers. The ultimate goal is providing a detailed experimental dataset for dripping onsets and bridging the knowledge gap in characterizing film flows on inclined, curved surfaces. Closing this gap will be achieved by developing a simplified 3D numerical model that will be validated through fully resolved numerical simulations and accompanying experiments. Due to the model formulation, the analysis of existing dripping mechanisms can be done with reduced computation times compared to fully resolved simulations.

• DFG Programme: Research Grants
• International Connection: Belgium, Netherlands
• Cooperation Partners: Professor Dr.-Ing. Wilko Rohlfs; Professor Dr. Benoit Scheid