How does biofouling change the sources of flow noise?

 

Barnacles and corrosion roughen ship hulls, altering the turbulent flow and the fluctuating pressure and shear forces that drive hull vibration and underwater noise. Laboratory studies suggest that roughness can greatly amplify the large-scale pressure fluctuations most relevant to noise, but we do not yet know how that effect changes at the Reynolds numbers of operating vessels.
We are developing synchronized measurements of wall pressure, wall shear stress, and turbulent velocity over near-smooth playa and rough terrain in Utah’s atmospheric surface layer. These field flows let us study the role of large turbulent structures at Reynolds numbers difficult to reach in a laboratory. By comparing the two surfaces and testing competing explanations for the pressure amplification, we aim to improve models of flow noise from bio-fouled marine vehicles.

Active Student(s): Alexander Tschinkel, Alexander Bracken, Jack Pfeifle

Sponsor: Dr. Julie Young (Office of Naval Research)

How do tiny liquid droplets reshape friction in high Reynolds number turbulent flow?

Supported by an ACS Petroleum Research Fund Doctoral New Investigator award, our lab is building a high-Reynolds-number wind-tunnel experiment that combines stereoscopic particle-image velocimetry, droplet tracking, and fast MEMS wall-shear sensing. By separating viscous, turbulent, and droplet-induced contributions to drag - and revealing how those contributions shift across flow scales - the project aims to uncover new physics of momentum loss and provide benchmark data for more energy-efficient petroleum transport models.

Active Student(s): TBA

Sponsor: American Chemical Society, Doctoral New Investigator Award

Pixelated Flow facilities for tomorrow's fluid dynamics

Most incompressible wind tunnels are designed to generate flow at a range of speeds and have been optimized for mild spatiotemporal variability, large-scale unsteadiness, low background noise, and full dynamic similarity. However, current technological challenges in fluid dynamics, such as with urban air mobility, are increasingly complex with vehicles subjected to atmospheric turbulence, vehicle wakes, three-dimensional building vortices, and thermal updrafts -- all simultaneously. To enable controlled studies that reproduce the critical physics of such flows we need a fundamentally new concept, like the recently proposed distributed flow facility made of computer cooling fans. We have taken this a step further by creating a facility using computer fans on all of the flow facility walls that can generate stable flow-speeds up to 11 m/s. Custom software is used to control complex 1D, 2D, and 3D gusts that can be induced on a fixed aircraft within the tunnel.

Active Student(s): Carson, Manish

Turbulence enhances insects' life?

Invasive insect species such as mosquitos and moths are a major menace that draw billions of dollars in prevention and healthcare, in addition to causing nearly a million deaths each year. Host-seeking behavior – where mosquitos approach humans using air-borne odor cues from even 50 meters away – remains unexplored with insects employing robust tracking strategies, apparently leveraging the flow turbulence instead of resisting it. Understanding this could yield not only efficient insect control strategies but also robust bio-inspired algorithms for bio-chemical hazard tracking.
Active Student(s): Jay