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GOMA 6.0 - A Full-Newton Finite Element Program for Free and Moving Boundary Problems with Coupled Fluid/ Solid Momentum, Energy, Mass, and Chemical Species Transport: User’s Guide

Sackinger, Philip A.; Noble, David R.; Notz, Patrick N.; Roberts, Scott A.; Rao, Rekha R.; Chen, Ken S.; Sun, Amy C.; Hopkins, Matthew M.; Subia, Samuel R.; Hopkins, Polly L.; Moffat, Harry K.; Roach, R.A.

Goma 6.0 is a finite element program which excels in analyses of multiphysical processes, particularly those involving the major branches of mechanics (viz. fluid/solid mechanics, energy transport and chemical species transport). Goma is based on a full-Newton-coupled algorithm which allows for simultaneous solution of the governing principles, making the code ideally suited for problems involving closely coupled bulk mechanics and interfacial phenomena. Example applications include, but are not limited to, coating and polymer processing flows, super-alloy processing, welding/soldering, electrochemical processes, and solid-network or solution film drying. This document serves as a user's guide and reference.

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TYPE SAND Report YEAR 2013
DOIOSTI

Comparison of monodisperse droplet generation in flow-focusing devices with hydrophilic and hydrophobic surfaces

Lab on a Chip

Roberts, Christine C.; Rao, Rekha R.; Loewenberg, Michael; Brooks, Carlton F.; Galambos, Paul; Grillet, Anne M.; Nemer, Martin N.

A thin flow-focusing microfluidic channel is evaluated for generating monodisperse liquid droplets. The microfluidic device is used in its native state, which is hydrophilic, or treated with OTS to make it hydrophobic. Having both hydrophilic and hydrophobic surfaces allows for creation of both oil-in-water and water-in-oil emulsions, facilitating a large parameter study of viscosity ratios (droplet fluid/continuous fluid) ranging from 0.05 to 96 and flow rate ratios (droplet fluid/continuous fluid) ranging from 0.01 to 2 in one geometry. The hydrophilic chip provides a partially-wetting surface (contact angle less than 90°) for the inner fluid. This surface, combined with the unusually thin channel height, promotes a flow regime where the inner fluid wets the top and bottom of the channel in the orifice and a stable jet is formed. Through confocal microscopy, this fluid stabilization is shown to be highly influenced by the contact angle of the liquids in the channel. Non-wetting jets undergo breakup and produce drops when the jet is comparable to or smaller than the channel thickness. In contrast, partially-wetting jets undergo breakup only when they are much smaller than the channel thickness. Drop sizes are found to scale with a modified capillary number based on the total flow rate regardless of wetting behavior. © The Royal Society of Chemistry.

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TYPE Journal Article YEAR 2012
ScopusOSTI
Results 126–150 of 227
Results 126–150 of 227