Date on Master's Thesis/Doctoral Dissertation

4-2015

Document Type

Master's Thesis

Degree Name

M. Eng.

Department

Chemical Engineering

Committee Chair

Berson, Robert E. (Eric)

Committee Co-Chair (if applicable)

Sharp, Keith

Committee Member

Watters, James

Author's Keywords

DOSI; Shear stress; Petri dishes

Subject

Fluid dynamics; Shear flow

Abstract

Effects of hemodynamic forces on cellular response are well studied. Wall shear stress is regularly accepted as the primary hemodynamic force affecting cellular response. Hemodynamic forces studies utilize Petri dishes on orbital shakers to grow cells for the experiments since this is an easily scalable system. However, characterizing the hemodynamics is difficult since the oscillatory swirling motion creates multidirectional and variable magnitude shear throughout the dish. Thus, a novel geometry dish that could create uniaxial shear with less variation in magnitude would be advantageous for studying shear stress effects on cellular response. The purpose of this thesis was to explore the ability for creating narrow shear ranges in terms of magnitude and direction, and to determine DOSI in novel geometry dishes. The new geometries consist of a narrow channel flat bottom dish and a narrow channel banked bottom dish. The study used computational fluid dynamics (Fluent) to simulate the fluid motion in the dishes. The study concluded with successfully identifying conditions surrounding regions of low variation of magnitude and direction of shear and DOSI patterns. For the NCF dish the least variation in shear magnitude, between radial locations, occurs at 60 RPM. In terms of the DOSI values, the NCF dish had increasingly higher DOSI values, meaning more uniaxial favored (tangential) flow across the surface of the dish as speed increased. The lowest variation occurred at 180 RPM. For the NCB dish the least variation in shear magnitude, between radial locations, occurred at 90 RPM. The NCB dish’s narrow range of shear stress is hypothesized to be the result of a more parallel fluid surface relative to the bottom surface of the dish. The NCB dish had DOSI values close to 1.0, meaning more uniaxial favored (tangential) flow, at the 80% and 90% radial locations for speeds between 120 and 180 rpm.

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