Joint MNE and EAS Seminar by Mr. Amir Pahlavan of MIT
When: Friday,
April 20, 2018
2:00 PM
-
3:00 PM
Where: Textiles Building 101E
Description: Joint Mechanical Engineering (MNE) and Engineering and Applied Sciences (EAS) Seminar
DATE:
April 20, 2018
TIME:
2:00 p.m. - 3:00 p.m.
LOCATION:
Textile Building, Room 101E
SPEAKER:
Mr. Amir Pahlavan, PhD Candidate Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT)
TOPIC:
Forced Wetting Transition and Pattern Formation in Immiscible Fluid Flows
ABSTRACT:
Immiscible fluid flows are ubiquitous in nature and industry, from porous media flows on km scales to micro/nanofluidic technologies. The common feature of these phenomena is the presence of contact lines, where fluids and surrounding solid meet. In the vicinity of the contact line, the bulk hydrodynamic descriptions break down and need to be augmented with the non-hydrodynamic interactions between the different phases. While the range of these interactions is limited to a few nanometers from the contact line, they can influence the flow behavior on the macroscopic length scales.
In this talk, we use a combination of experiments and modeling to revisit two classical problems and show the role of contact line motion on the front instability and pattern formation. In the first part, we revisit the Taylor-Bretherton problem, i.e. fluid-fluid displacement in a smooth capillary tube. We show that the presence of a moving contact line leads to a rich flow behavior: at low displacement rates, the interface moves as a "traveling wave", but beyond a critical rate, a wetting transition occurs and a film of the defending viscous fluid is left behind on the walls. This film is unstable and starts receding from the walls, forming a growing dewetting rim, which ultimately leads to a pinch-off instability. In the second part of the talk, we revisit the Saffman-Taylor instability, i.e. fluid-fluid displacement in a Hele-Shaw cell. We show how a new mode of instability arises when contact line motion is considered.
Our work sheds some light on the complexities of immiscible flows in disordered media and points to new directions of approaching this problem within the general realm of soft-matter physics.
BIO:
Amir Pahlavan is a PhD candidate in the Mechanical Engineering department at MIT, where his research focuses on pattern formation in immiscible flows through disordered media. He earned his MS in Theoretical and Applied Mechanics from University of Illinois at Urbana-Champaign, where he studied the liquid-solid interactions and slip phenomenon at the nano-scale, as well as the collective dynamics and chemotaxis in suspensions of active materials. His research focuses on understanding the emergent macroscopic behavior of soft materials from their micro/nano-scale interactions with their complex environments and using these insights to improve our predictive capabilities of engineering processes.
For more information please contact Dr. Jun Li, MNE Seminar Coordinator (jun.li@umassd.edu, 508-999-8692).
All are welcome and light refreshments will be served.
Students taking MNE-500 are REQUIRED to attend! All other MNE and EAS students are encouraged to attend.
Thank you,
Sue Cunha, Administrative Assistant
Mechanical Engineering Department
scunha@umassd.edu
508-999-8492
DATE:
April 20, 2018
TIME:
2:00 p.m. - 3:00 p.m.
LOCATION:
Textile Building, Room 101E
SPEAKER:
Mr. Amir Pahlavan, PhD Candidate Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT)
TOPIC:
Forced Wetting Transition and Pattern Formation in Immiscible Fluid Flows
ABSTRACT:
Immiscible fluid flows are ubiquitous in nature and industry, from porous media flows on km scales to micro/nanofluidic technologies. The common feature of these phenomena is the presence of contact lines, where fluids and surrounding solid meet. In the vicinity of the contact line, the bulk hydrodynamic descriptions break down and need to be augmented with the non-hydrodynamic interactions between the different phases. While the range of these interactions is limited to a few nanometers from the contact line, they can influence the flow behavior on the macroscopic length scales.
In this talk, we use a combination of experiments and modeling to revisit two classical problems and show the role of contact line motion on the front instability and pattern formation. In the first part, we revisit the Taylor-Bretherton problem, i.e. fluid-fluid displacement in a smooth capillary tube. We show that the presence of a moving contact line leads to a rich flow behavior: at low displacement rates, the interface moves as a "traveling wave", but beyond a critical rate, a wetting transition occurs and a film of the defending viscous fluid is left behind on the walls. This film is unstable and starts receding from the walls, forming a growing dewetting rim, which ultimately leads to a pinch-off instability. In the second part of the talk, we revisit the Saffman-Taylor instability, i.e. fluid-fluid displacement in a Hele-Shaw cell. We show how a new mode of instability arises when contact line motion is considered.
Our work sheds some light on the complexities of immiscible flows in disordered media and points to new directions of approaching this problem within the general realm of soft-matter physics.
BIO:
Amir Pahlavan is a PhD candidate in the Mechanical Engineering department at MIT, where his research focuses on pattern formation in immiscible flows through disordered media. He earned his MS in Theoretical and Applied Mechanics from University of Illinois at Urbana-Champaign, where he studied the liquid-solid interactions and slip phenomenon at the nano-scale, as well as the collective dynamics and chemotaxis in suspensions of active materials. His research focuses on understanding the emergent macroscopic behavior of soft materials from their micro/nano-scale interactions with their complex environments and using these insights to improve our predictive capabilities of engineering processes.
For more information please contact Dr. Jun Li, MNE Seminar Coordinator (jun.li@umassd.edu, 508-999-8692).
All are welcome and light refreshments will be served.
Students taking MNE-500 are REQUIRED to attend! All other MNE and EAS students are encouraged to attend.
Thank you,
Sue Cunha, Administrative Assistant
Mechanical Engineering Department
scunha@umassd.edu
508-999-8492
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