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Jul
23
2:00PM
Mechanical Engineerin MS Thesis Defense by Mr. Daniel J. O'Coin

Mechanical Engineering MS Thesis Defense by Mr. Daniel J. O'Coin DATE: July 23, 2024 TIME: 2:00 p.m. - 4:00 p.m. LOCATIONS: Science & Engineering (SENG) Building, Room 110 and on Zoom: https://umassd.zoom.us/j/94136706089?pwd=xwKSJQdtQ0iDdJ5gj0XU4cqfQBweNY.1 (Password: 443450) TOPIC: An Experimental Study of Bubble Formation on Super-Hydrophobic Surfaces ABSTRACT: This thesis experimentally studied the bubble formation on a superhydrophobic surface (SHS), which had a large equilibrium water contact angle (>150). Bubble formation is a crucial process for many industrial and biomedical applications, for example, pool boiling heat transfer, froth floatation, surface cleaning, and drug deliver. In this thesis, we captured the bubble formation under constant gas flow rates by using a high-speed camera. The SHS was fabricated by first sandblasting an aluminum surface and then coating the rough surface with hydrophobic nanoparticles. We systemically investigated the impacts of radius of SHS (RSHS), gas flow rate (Q), and surface tension () on bubble formation and bubble detached volume (Vd). First, we found that depending on RSHS, bubble formation followed two different modes: Mode A and Mode B. In Mode A for small RSHS, the contact line quickly pined at the rim of SHS after an initial expansion, and Vd increased as increasing RSHS. In Mode B for large RSHS, the contact line continuously expanded as the bubble grows. Second, we found that Vd increased as increasing Q, and the relation between Vd and Q followed similar trends after proper normalizations, regardless of the types of surfaces and the values of equilibrium contact angle. During the necking, the bubble volume was nearly constant for small Q but increased significantly for large Q. Third, we found that as reducing , the equilibrium contact angle and surface area covered by gas reduced, leading to a smaller bubble base radius and smaller Vd. Moreover, we performed a force balance analysis and found that the main forces acting on the bubble were one lifting force (pressure force) and two retaining forces (surface tension force and buoyancy force). We found that the necking radius and time to pinch-off followed a power-law relation, which agreed well with that for the pinch-off of bubble on a nozzle. Last, we found that the Tate volume, derived based on the balance between surface tension and buoyancy, well predicted Vd. Overall, our results provided a better understanding of bubble formation on SHS and can be applied for: (i) the control of bubble generation by using complexed surfaces; and (ii) restoration of gas layer and extension of the longevity of SHS for applications such as drag reduction, anti-icing, anti-biofouling, and anti-corrosion. ADVISORS: - Dr. Hangjian Ling, Assistant Professor, Department of Mechanical Engineering, UMass Dartmouth COMMITTEE MEMBER: - Dr. Sankha Bhowmick, Professor, Department of Mechanical Engineering, UMass Dartmouth - Dr. Mehdi Raessi, Professor, Department of Mechanical Engineering, UMass Dartmouth Open to the public. All MNE students are encouraged to attend. For more information, please contact Dr. Hangjian Ling (hling1@umassd.edu).

Aug
6
4:00PM
National Night Out 2024

Food, Games, K-9 Demo, Music, Community Resources and More... Made Possible with the support of the Mayor Jon Mitchell, the New Bedford Police Department, the New Bedford Fire Department, District Attorney Tom Quinn, the City of New Bedford Health Department, New Bedford City Council, New Bedford Public Schools, NorthStar Learning Centers, Neighborhoods United, New Bedford Office of Community Services, Partners In Health, State Police, Bristol County Sheriff's Office, Alfred J. Gomes Neighborhood Association, OBVC, New Bedford Shannon Outreach Program, PAACA, NAACP NEW BEDFORD BRANCH and many others. LOCATION: Hazelwood Park (Brock Avenue Entrance), New Bedford, MA CONTACT: Renee Ledbetter at

Aug
30
12:00PM
Women's Soccer v. Regis College

Women's Soccer season opener against Regis College

Aug
30
3:00PM
Men's Soccer v. Framingham State

Men's Soccer home opener against Framingham State.

Aug
31
1:00PM
Women's Soccer v. Salem State

Women's Soccer v. Salem State

Sep
2
11:00AM
DIY Arnie Palmers

Cool off with an Arnie Palmer! Questions? Email us at dining@umassd.edu or message us on Instagram @UMassDEats

Sep
3
11:30AM
All-Campus BBQ

Each year, Convocation is held in the Amphitheatre and is a ceremony that celebrates the beginning of the academic year and welcomes our new students to campus. After the ceremony ends at 11:30 a.m., all students, faculty, and staff are invited to the All-Campus BBQ on the Quad. Contact publicaffairs@umassd.edu for more info.

Sep
3
3:30PM
Women's Tennis v. Lesley University

Women's tennis home opening match

Sep
4
4:30PM
Welcome Back Dinner

Welcome Back Corsairs! Join us for our Welcome Back Dinner in The Grove! Questions? Email us at dining@umassd.edu or message us on Instagram @UMassDEats

Sep
4
7:00PM
Field Hockey v. Elms College

Field hockey home opener v. Elms College

Sep
5
4:30PM
Retail Round Up

New to campus? Want to learn more about our dining locations? Join us in The Grove for our Retail Round Up dinner and get a taste of all our retail locations! Questions? Email us at dining@umassd.edu or message us on Instagram @UMassDEats

Sep
7
12:00PM
Men's Soccer v. Salem State

Men's Soccer v. Salem State

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