Passive Volumetric Composite Design for Hydrodynamic Wake Control

Dean Culver
Friday, February 27, 2015 - 11:45am
Hudson 2201
Seminar Contact(s): 
Daniel Real, daniel.real@duke.edu
Semester & Year: 
Fall 2015

Directions to the Seminar: From the MEMS Office, go down the hall towards the annex. Take the set of stairs at the end of the hall to the second floor. Walk down the hallway on your right. Take the first left, and then another immediate left. Froom 2201 will be at the end of this short hallway. Signs will be posted to help guide you.



Passive Volumetric Composite Design for Hydrodynamic Wake Control


Dean Culver


Abstract

Wake reduction is a crucial link in the chain leading to undetectable watercraft. Here, we explore a volumetric approach to controlling the wake in a stationary flow past cylindrical and spherical objects. In this approach, a fixed-shape object is coated with a composite fluid-solid structure that is permeable to the flow. We pursue a macroscopic design approach where all solid boundaries are parameterized and modeled explicitly. Local, gradient-based optimization techniques are employed that permit topological changes in the manifold describing the composite solid component(s) while still allowing the use of adjoint methods for efficient evaluations of the sensitivity matrix. This formalism works well from the Stokes (creeping flow) limit up to small Reynolds number (Re) turbulent flow (Re≈100-10,000) when simulated using small-Re Reynolds-averaged Navier-Stokes (RANS) models.  The added benefit of our design methodology is that it yields structures than can be fabricated immediately using fused deposition modeling (FDM). Our prototypes have been verified in an experimental water tunnel facility, where the use of Particle Image Velocimetry (PIV) described the velocity profile. Comparisons with our computational models show excellent agreement for the spherical shapes, and reasonable match for cylindrical shapes, with well-understood sources of error. Two important figures of merit are considered: the Domain Wide Wake (DWW) and the Maximum Local Wake (MLW). For the sphere, experiments demonstrate a 31% reduction in the MLW, whereas computer models suggests a 16% reduction. For the cylinder, experiments demonstrated a 10% reduction in the MLW, whereas the computer models suggested a 25% reduction.


Biography

Dean is a second year PhD Student studying applied nonlinear dynamics at Duke University where he contributes to research in applied asymptotics and hydrodynamic cloaking. He settled on these areas of interest after earning his bachelor's and professional master's degrees at RIT focusing on dynamics and controls. As a Pittsburgh native and working resident between 2011 and 2013, Dean has experience in the transportation, aeronautics, and nuclear energy industries through various design engineering positions and internships, but hopes to one day settle into a career as a professor continuing work on nonlinear dynamics and contribute to the development of renewable energy technology.