Controlling secondary flows by the use of non-wetting surfaces

University Of Houston, Houston TX

Investigators

Abstract

Turbulent secondary flows are naturally or artificially induced flows perpendicular to the main direction of primary flow. Many important industrial processes have curved-pipe systems and rotating machinery designed to enhance and optimize mixing of chemicals and other fluids. These systems may also produce turbulent secondary flows. Depending on how the secondary flow is generated, it may be ordered and stationary in space creating stagnant regions, which inhibits mixing even if the flow has significant turbulence. This research will provide a better understanding of the physics behind the generation of secondary flows and how to control them. Computations and experiments will be used to investigate using non-wetting (hydrophobic) surfaces to impact and control these flow features. Every summer, a camp will be held for more than 30 underrepresented minority K-12 students to encourage STEM. The goal of this project is to investigate the use of non-wetting surfaces to induce, affect, and control secondary flows through selectively patterning the solid boundaries. By using a combination of direct numerical simulations and laboratory experiments, questions on which types and patterns of treatments are most effective the secondary flows. The effectiveness of different kinds of surface treatments, both in the direction of the flow, and perpendicular to the flow, will be evaluated by measuring frictional losses and flow homogeneity. Investigations will be based on a canonical system where pinned secondary flows are known to exist, namely Taylor-Couette turbulence, i.e. the flow between two concentric cylinders. Simulations will be carried out to test a wide variety of surface patterns to determine the most efficient arrangements by using boundary conditions that resemble both ideal and real treatments. Experiments will measure the real-world efficacy of these treatments with great precision. Finally, by studying aging surfaces, the lifetime of the treatment effectiveness can be estimated. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.