Flow visualization studies in scaled-up gravure grooves and cells
Abstract
Gravure coating and printing are processes commonly used to produce micron-scale coatings and patterns in a continuous manner, and may be well-suited for the large-scale fabrication of nano- and microdevices on flexible substrates. A rotating cylinder engraved with small grooves (for coating) or cells (for printing) is used to transfer liquid onto a substrate which moves at high speeds. To have precise control over the thickness of coatings and printed features, and to avoid defects due to incomplete liquid transfer, it is crucial to understand the fundamental principles that govern the liquid transfer process. In order to mimic the basic aspects of the problem, a glass top with a curved surface is passed over scaled-up gravure grooves and cells. For the scaled-up groove, flow visualization reveals the presence of a large eddy attached to the trailing edge of the glass top, which appears to be consistent with recent computations by Powell et al. For the scaled-up cell, flow visualization reveals that the liquid flows very quickly into the meniscus region between the glass top and the cell. It is also found that the degree of cell emptying is inversely proportional to the thickness of the liquid film on the cell lands, and inversely proportional to the capillary number. If the liquid is water and the film on the lands is sufficiently thin, the cell may be nearly emptied.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 2003
- Bibcode:
- 2003APS..DFD.DQ004Y