Show simple item record

dc.contributor.advisorKieweg, Sarah L
dc.contributor.authorHu, Bin
dc.date.accessioned2017-01-02T19:49:01Z
dc.date.available2017-01-02T19:49:01Z
dc.date.issued2016-08-31
dc.date.submitted2016
dc.identifier.otherhttp://dissertations.umi.com/ku:14844
dc.identifier.urihttp://hdl.handle.net/1808/22335
dc.description.abstractThin film coating flow is of importance in many fields, as well as for the design of polymeric drug delivery vehicles, such as anti-HIV topical microbicides. This dissertation describes a few models to investigate the coating flow of a microbicidal gel. At the beginning of this dissertation, we studied the gravity-driven thin film flow model. In our 2D (i.e. 1D spreading) power-law model, we found that surface tension effect not only impacted the spreading speed of the microbicide gel, but also had an influence on the shape of the 2D spreading profile. We observed a capillary ridge at the front of the fluid bolus. We focused on the capillary ridge in 2D flow and performed a series of simulations and showed how the capillary ridge height varies with other parameters. As shown in our results, we found that capillary ridge height increased with higher surface tension, steeper inclination angle, larger initial thickness, and more Newtonian fluids. In the second study, a model of fingering instability at a moving contact line was developed. Previous literature showed that the emergence of a capillary ridge is strongly related to the contact line fingering instability in Newtonian fluids. Fingering instabilities during epithelial coating may change the microbicide gel distribution and therefore impact how well it can protect the epithelium. Results from our 2D model indicated more shear-thinning fluids should have suppressed finger growth and longer finger wavelength, and this should be evident in linear stability analysis (LSA) and 3D (i.e. 2D spreading) numerical simulations. In our 3D model studies, we developed a LSA model for the gravity-driven flow of shear-thinning films, and carried out a parametric study to investigate the impact of shear-thinning on the growth rate of the emerging fingering pattern. A fully 3D model was also developed to compare and verify the LSA results using single perturbations, and to explore the result of multiple-mode, randomly imposed perturbations. Both the LSA and 3D numerical results confirmed that the contact line fingers grow faster for Newtonian fluids than the shear-thinning fluids on both vertical and inclined planes. In addition, both the LSA and 3D model indicated that the Newtonian fluids form fingers with shorter wavelengths than the shear-thinning fluids when the plane is inclined; no difference in the most unstable (i.e. emerging) wavelength was observed at vertical. For the first time for shear-thinning fluids, these results connect trends in capillary ridge and contact line finger formation in 2D models, LSA, and 3D simulations. At the end of this dissertation, we used a more complicated constitutive model – the Phan-Thien-Tanner (PTT) rheological model -- to describe the viscoelastic behavior on two different models for the vehicle delivery process: the gravity-driven spreading model, and epithelial squeezing flow model. We used ANSYS POLYFLOW software package to solve the resulting PDEs. Elastic viscous split stress (EVSS) approach was used to split the stress tensor of the gel into a Newtonian solvent and an elastic polymeric contribution. Several parametric studies were carried out to investigate the combined effect of shear-thinning and elastic behavior on both flows. In the gravity-driven model, the spreading speed of the microbicide gel down an incline obtained from the current PTT model was slower than the one we found in the previous power-law model. This is consistent with our previous numerical and experimental studies, which indicates the elastic effect of the microbicide gel is important and a more accurate constitutive model is needed than power-law model in simulating the microbicide spreading. In the epithelial squeezing flow model, we used the FSI (fluid-structure interaction) approach to study the spreading of the microbicide gel on the epithelial surface under the squeezing force of the vaginal tissue. The results showed that lower tissue elasticity and lower Deborah number of the microbicide gel can cause more epithelial deformation. Then microbicide gel flows faster with higher tissue elasticity during the insertion process. The results of this dissertation can provide us insights on how to optimize non-Newtonian fluid properties for better performance during the drug delivery process.
dc.format.extent124 pages
dc.language.isoen
dc.publisherUniversity of Kansas
dc.rightsCopyright held by the author.
dc.subjectMechanical engineering
dc.subjectBiomechanics
dc.subjectBiomedical engineering
dc.subjectMicrobicide gels
dc.subjectNon-Newtonian fluids
dc.subjectNumerical analysis
dc.subjectSurface tension
dc.subjectThin film flow
dc.subjectViscoelastic behavior
dc.titleEFFECTS OF SURFACE TENSION AND VISCOELASTIC BEHAVIOR ON THE THIN FILM COATING FLOW OF MICROBICIDE GELS
dc.typeDissertation
dc.contributor.cmtememberDougherty, Ronald L
dc.contributor.cmtememberLuchies, Carl W
dc.contributor.cmtememberVan Vleck, Erik
dc.contributor.cmtememberWilson, Sara E
dc.thesis.degreeDisciplineMechanical Engineering
dc.thesis.degreeLevelPh.D.
dc.identifier.orcid
dc.rights.accessrightsopenAccess


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record