Doctoral Candidate

Winner, South Dakota

Co-Advisor: Professor Eric Shaqfeh

Education

B.S. Chemical Engineering, South Dakota School of Mines and Technology, 2008
B.S. Applied and Computational Mathematics, South Dakota School of Mines and Technology, 2008

Research Focus

Removing surface contaminants is an age-old problem that continues to plague various technological industries today, specifically those technologies requiring high-grade semiconductors. Thus, the need for an economical and non-destructive cleansing method is present. To achieve this goal, our group is focused on understanding the use of Newtonian and non-Newtonian fluids as cleaning agents from an experimental perspective, while collaborative work is completed in an attempt to create predictive models for a given agents effectiveness.

Currently, my work, in collaboration with Theresa Hsu, focuses on qualitatively and quantitatively understanding the flow structure of the removal of the cleaning agent by rinsing with a high-velocity water jet, impinged normal to the surface. When a jet impinges normal to a surface, an axisymmetric flow propagates, leading to the formation of a hydraulic jump at some critical radial distance. This hydraulic jump is commonly seen in any such flow, having the characteristic of a high velocity, shallow laminar flow that abruptly becomes a much slower, turbulent flow at a depth much greater than the former. This study seeks to investigate the interactions of the two fluid system during the transient growth of the flow profile. This growth is seen to vary drastically in magnitude, velocity, and topology, while undergoing varying instabilities, depending on the properties of the coating fluid.

We aim to fully understand the flow profile of the system, which becomes increasingly complex when the non-Newtonian behavior of the cleaning
agent is considered, from both an experimental and theoretical standpoint. Using high-speed cameras and computer imaging software, we are able to quantitatively understand the transient growth of the hydraulic jump, while qualitatively understanding the interaction of the two-fluid system. Simulations are also being completed in an attempt to understand these complex flow kinematics.

Publications

Hsu, T.T., Walker, T.W., Frank, C.W., Fuller, G.G. “Role of fluid elasticity on the dynamics of rinsing flow by an impinging jet.” Phys. Fluids. 23(3), 2011. DOI:10.1063/1.3567215. (Article)

Walker, T.W.  “Harnessing Natural Energy.”  ­Chemical Engineering Progress (CEP),  AIChE: March 2008.

Walker, T.W.  “Clean Energy Sources and Mass Electrical Storage.” Journal of Engineering and Public Policy, vol. 11, 2007, <http://www.wise-intern.org>.

Artwork

Hsu, T.T., Walker, T.W., Frank, C.W., Fuller, G.G. “Screen shots of the rinsing flows with the testing coating fluid being (clockwise from upper left) glycerol-water, Boger fluid, semidilute PAM solution, and water.” Cover. Phys. Fluids. 23(3), 2011. (Link)

Other Stanford Activities

Stanford Alpine Club (SAC)
Outdoor Education Program (OEP)

Contact Information

twwalker@stanford.edu