Date of Award

5-2024

Degree Type

Dissertation

Degree Name

Ph.D.

Degree Program

Engineering and Applied Science - Naval Architecture & Marine

Department

Naval Architecture and Marine Engineering

Major Professor

Dr. Brandon Taravella

Second Advisor

Dr. Erin Cox

Third Advisor

Dr. Lothar Birk

Fourth Advisor

Dr. Kazim Akyuzlu

Fifth Advisor

Dr. Vincent Yu

Abstract

This study is an investigation of the effect of biofouling on the boundary layer of a flat plate and a NACA 4-digit series foil. Three identical hydrofoils made of resin were placed in the Gulf of Mexico at Grand Isle, Louisiana, and observed and analyzed by marine biologists at the University of New Orleans for their species composition. The resulting biofouling that grew was primarily made up of barnacles and bryozoans. The foils were submerged in an open channel flume at zero incidence and subjected to a series of experiments whose arc-length Reynolds numbers ranged from approximately 13000 to 32000. The flow regime around the fouled foils was laminar and captured in a series of experiments using two-dimensional particle image velocimetry. The resulting data was compared to the flow regime around an identical foil with no biofouling on its surface, which was tested using the same methods at zero incidence. The flow regime of the “clean foil” was also captured using two-dimensional particle image velocimetry. The effects of the biofouling on shear stress, boundary layer thickness, and velocity profiles were analyzed. The strengths and weaknesses of using the particle image velocimetry method for capturing flow around biofouling was also discussed. Two dimensional simulations of the fouled foils were created in the commercial computational fluid dynamics software ANSYS Fluent for comparison to the results of the particle image velocimetry experiments on the fouled foils. The experiments on the fouled foils found that the biofouling causes the boundary layer thickness to increase along the length of the foil in comparison to the boundary layer of the clean foil. However, at these Reynolds numbers, even relatively large and obstructive biofouling such as barnacles do not cause significant disruption of the boundary layer or the flow regime. The two-dimensional simulations of the fouled foils compare favorably to the corresponding experimental results, although they slightly overpredict the effect the biofouling has on the separation regions of the fouled foil, which are located downstream of the location of maximum thickness. For example, the separation regions, and therefore the boundary layers, were somewhat thicker in the simulations than in the experiments. It was found that upstream of the location of maximum thickness of the foil, the simulations and experiments showed better agreement in terms of thickness of the boundary layer and the nature of the velocity profiles. It was determined that particle image velocimetry is effective and recording velocity profiles of biofouled surfaces along with shear stress data. Further studies should investigate other types of fouling and whether three-dimensional computational fluid dynamics simulations would be more effective for this purpose, and worth the additional computational cost.

Keywords: boundary layer, biofouling, computational fluid dynamics, hydrofoil

Rights

The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

Download

Share

COinS