Analysis of optical waveguide fabrication processes
The purpose of the study was to investigate the deposition of fine particles from a flow, onto surfaces, and to relate the deposition process to the flow conditions. Both, internal & external boundary layer type flows have been studied. These can be related to the conditions encountered in the Modified Chemical Vapor Deposition (MCVD) and Outside Vapor Deposition (OVD) processes used in optical waveguide fabrication. For internal flows, the equations that govern the energy and particle transport are relatively simple and have been studied by previous researchers who suggested that thermophoresis is the dominant particle transport mechanism. This has been confirmed by our study too. The new aspect of our research is that we have included the particle size calculations in our model. External flows are more difficult to analyze because of the added burden of evaluating the flow field. Another difficulty is the growth of the boundary layer. To avoid this, a coordinate transformation has been used that makes the domain of computation rectangular and the boundary layer growth in these coordinates negligible. The governing equations are solved, once again, using a finite difference technique. The results obtained agree well with those of Homsy et. al., who used a Blasius series technique in terms of universal functions. Results indicate that the deposition rate is greater for larger temperature differences between the flow and deposition surface. The dependance on Reynolds number of the free stream has also been analysed.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:deposition of fine particles optical waveguide fabrication outside vapor
Date of Publication:01/01/1986