Due to the selective use of liquid films in specialized technical equipment (e.g. new generation nuclear reactors), a fundamental understanding of underlying momentum and heat transport processes inside these thin liquid layers (with a thickness of approximately 0.5 mm) is required. In particular, the influence of surface waves (which develop due to the film’s natural instability) on these transport processes is of interest. For a number of years, experimental and numerical observations in wavy falling liquid films have suggested that momentum and heat transfer in the capillary wave region, preceding large wave humps, undergo drastic modulations. Indeed, some results have indicated that upward flow, i.e. counter to the gravitational acceleration, takes place in this region. Further, evidence of a substantial increase in wall-side and interfacial transfer coefficients has also been noted. Recently, Dietze et al. [1,2] have established that flow separation takes place in the capillary wave region of 2-dimensional laminar falling liquid films, partially explaining the above mentioned observations. Thereby, it was shown that the strong third order deformation (i.e. change in curvature) of the liquid-gas interface in the capillary wave region causes an adverse pressure gradient sufficiently large to induce flow detachment from the wall. In the present paper, a detailed experimental and numerical account of the capillary flow separation’s kinematics and governing dynamics as well as its effect on heat transfer for two different 2-dimensional flow conditions is presented. Experimentally, velocity measurements (using Laser Doppler Velocimetry (LDV) and Particle Image Velocimetry (PIV)) and film thickness measurements (using a Confocal Chromatic Imaging technique) were performed in a specifically designed optical test setup. On the numerical side, simulations of the full Navier-Stokes equations as well as the energy equation using the Volume of Fluid (VOF) method were performed. In addition to the 2-dimensional investigations, the characteristics of capillary flow separation under 3-dimensional wave dynamics were studied based on the 3-dimensional numerical simulation of a water film, which was previously investigated experimentally by Park and Nosoko [3]. Results show that flow separation persists over a wide area of the 3-dimensional capillary wave region, with multiple capillary separation eddies occurring in the shape of vortex tubes. In addition, strong spanwise flow induced by the same governing mechanism is shown to occur in this region, which could explain the drastic intensification of transfer to 3-dimensional liquid films.
Skip Nav Destination
2010 14th International Heat Transfer Conference
August 8–13, 2010
Washington, DC, USA
Conference Sponsors:
- Heat Transfer Division
ISBN:
978-0-7918-4938-5
PROCEEDINGS PAPER
Capillary Flow Separation in 2- and 3-Dimensional Laminar Falling Liquid Films
Georg F. Dietze,
Georg F. Dietze
RWTH Aachen University, Aachen, Germany
Search for other works by this author on:
Reinhold Kneer
Reinhold Kneer
RWTH Aachen University, Aachen, Germany
Search for other works by this author on:
Georg F. Dietze
RWTH Aachen University, Aachen, Germany
Reinhold Kneer
RWTH Aachen University, Aachen, Germany
Paper No:
IHTC14-22064, pp. 753-768; 16 pages
Published Online:
March 1, 2011
Citation
Dietze, GF, & Kneer, R. "Capillary Flow Separation in 2- and 3-Dimensional Laminar Falling Liquid Films." Proceedings of the 2010 14th International Heat Transfer Conference. 2010 14th International Heat Transfer Conference, Volume 3. Washington, DC, USA. August 8–13, 2010. pp. 753-768. ASME. https://doi.org/10.1115/IHTC14-22064
Download citation file:
16
Views
Related Proceedings Papers
Related Articles
Large Eddy Simulation of a Flow Past a Free Surface Piercing Circular Cylinder
J. Fluids Eng (March,2002)
Steady Propagation of a Liquid Plug in a Two-Dimensional Channel
J Biomech Eng (October,2004)
Modeling Wall Film Formation and Breakup Using an Integrated Interface-Tracking/Discrete-Phase Approach
J. Eng. Gas Turbines Power (March,2011)
Related Chapters
Cooling a Radar’s Electronic Board
Electromagnetic Waves and Heat Transfer: Sensitivites to Governing Variables in Everyday Life
Laminar Fluid Flow and Heat Transfer
Applications of Mathematical Heat Transfer and Fluid Flow Models in Engineering and Medicine
Introduction
Heat Transfer & Hydraulic Resistance at Supercritical Pressures in Power Engineering Applications