Project:	Optimize the turbulent drag reduction effect of the dynamic free-slip surface method
Disciplines:	Mechanical Engineering, Physics, Computer Science, Mathematics
Mentor:	Cong Wang, Assistant Professor, (EAS), cong-wang-1@uiowa.edu, Phone: 626-437-8816
Background:	NOTE 1: This project is being offered by a Caltech alum and is open only to Caltech students. The project will be conducted at the University of Iowa in Iowa City, Iowa. NOTE 2: Dr. Wang is offering three different projects. Please include "Caltech SURF + project title" in the subject line when emailing Dr. Wang. The turbulent drag force is the major limiting factor for the energy efficiency of large-scale transportation systems, such as containership, commercial airplane, and oil pipeline. As such, effective turbulent flow control and drag reduction can substantially increase energy efficiency (e.g., more than 50% - 80%). Recently, a novel dynamic free-slip surface method, which employes an array of actuated deformable free-slip interfaces, was developed at Caltech (Wang 2019). This technique can reduce the turbulent drag by more than 40%. However, it is unclear if the drag reduction effect can be sustained in flows with higher speed (higher Reynolds number). In addition, the design and control (e.g., geometrical design and actuation frequency) of this promising technique can be further optimized.
Description:	The drag reduction effect of the dynamic free-slip surface method can be affected by many parameters, such as the distribution pattern, the actuation control condition, and the turbulent flow condition. To search for the optimal drag reduction strategy, we will focus on understanding the dynamic free-slip surface interacting with wall-bounded laminar or turbulent flows. Approaches of experimental measurement (e.g., particle image velocimetry) and theoretical analysis will be employed to uncover the physics of the interaction process.
References:	Wang C, Gharib M. Effect of the dynamic slip boundary condition on the near-wall turbulent boundary layer. Journal of Fluid Mechanics. 2020;901:A11. Wang, Cong, David Jeon, Morgane Grivel, Francisco Pereira, and Morteza Gharib. "Systems, methods, and apparatuses for reducing hydrodynamic frictional drag." U.S. Patent 10,787,231, issued September 29, 2020. Wang, Cong. "On the manipulation of a turbulent boundary layer by unsteady boundary conditions." PhD diss., California Institute of Technology, 2019.
Student Requirements:	Basic knowledge and interest in physics, mechanics, and vector calculus is required. Skills in hands-on experiment (mechanical design, optics, camera, laser, etc) and data analysis (matlab, python, etc) are preferred.
Programs:	This AO can be done under the following programs:   Program    Available To        SURF    Caltech students only  Click on a program name for program info and application requirements.