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MULTISCALE STRUCTURED SURFACES AND THEIR EFFECT ON DRAG & FLUID FLOW

Jenner, Elliot (2015) MULTISCALE STRUCTURED SURFACES AND THEIR EFFECT ON DRAG & FLUID FLOW. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

In this thesis, we examine surface modification as a method for reducing fluid drag on a surface. Reducing drag is of great interest for many applications, including in ship construction, fluid pipelines, self-cleaning surfaces, and for use in MicroElectroMechanical Systems. Multiscale structured hydrophobic surfaces can reduce fluid drag, depending on surface chemistry and structure geometry. We examine the properties of artificial version of bio-inspired hydrophobic surfaces with multiple wetting states, including some not previously tested or known to exist.

Multiscale surfaces have structure on a small and a large scale. We evaluate the effect of changes in the large scale features on drag properties. We also vary the fluid state on the surfaces by application or removal of a passively retained secondary liquid. We examine the fluid properties in a number of ways, including torque and shear rate measurement in a custom made Cone \& Plate Rheometer.

Conventional shear rate measurements in a Cone \& Plate Rheometer depend on knowledge of the interface; since we are measuring unknown surfaces, we must develop an alternative method. We measure the components of the shear rate tensor S directly using Photon Correlation Spectroscopy, where we develop a general theoretical treatment for measuring 3-D flows with this technique. Previous work on Photon Correlation Spectroscopy has involved only approximate solutions, requiring free parameters to be scaled by a known case, or special cases, such as 2-D flow.

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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Jenner, Elliotelj17@pitt.eduELJ17
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairD'Urso, Briandursobr@pitt.eduDURSOBR
Committee MemberDutt, Gurudev gdutt@pitt.eduGDUTT
Committee MemberCoulson, RobertCOALSON@pitt.eduCOALSON
Committee MemberShepard, Paulshepard@pitt.eduSHEPARD
Committee MemberYang, Judithjudyyang@pitt.eduJUDYYANG
Date: 19 June 2015
Date Type: Publication
Defense Date: 26 February 2015
Approval Date: 19 June 2015
Submission Date: 4 February 2015
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 155
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Physics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Drag Reduction, Hydrophobicity, Multiscale Surfaces, Aluminum Oxide, Photon Correlation Spectroscopy, Shear Rate, Laminar Flow, Fluid Drag
Date Deposited: 19 Jun 2015 20:08
Last Modified: 15 Nov 2016 14:26
URI: http://d-scholarship.pitt.edu/id/eprint/23976

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