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Research Spending & Results

Award Detail

Doing Business As Name:University of Pittsburgh
  • Sachin S Velankar
  • (412) 624-9984
Award Date:06/24/2020
Estimated Total Award Amount: $ 291,968
Funds Obligated to Date: $ 291,968
  • FY 2020=$291,968
Start Date:09/01/2020
End Date:08/31/2023
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.041
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Collaborative Research: Micromechanics of Meniscus-bound Particle Clusters
Federal Award ID Number:2031144
DUNS ID:004514360
Parent DUNS ID:004514360
Program Officer:
  • William Olbricht
  • (703) 292-4842

Awardee Location

Street:300 Murdoch Building
Awardee Cong. District:18

Primary Place of Performance

Organization Name:University of Pittsburgh
Street:3420 Forbes Avenue
Cong. District:18

Abstract at Time of Award

Surface tension phenomena are important in a variety of physical processes including blending of immiscible fluids, formation of sprays and aerosols and foaming of plastics. This collaborative project concerns particle-liquid mixtures that are generally called particulate suspensions. Examples include slurries encountered in mineral and ceramics processing, particle-filled molten plastics, and printing inks. In such particulate suspensions, the addition of a second immiscible liquid induces particle "sticking" and aggregation due to surface tension and capillary forces. A familiar example is a sandcastle whose strength comes from small water droplets which bind the sand grains together by capillary forces. This project will conduct fundamental studies of interparticle capillary forces in mixing flows. Particle clusters bound by capillary forces will be placed in well-defined flows and studied using new methods in automated flow control. This work aims to understand the flow dynamics of particle clusters and the limits of their stability, which refers to the conditions under which clusters rupture due to the applied flow. Over the past decade, surface tension-induced particle clustering has been exploited for a wide range materials and materials-processing applications including macroporous ceramics, 3D printing, conductive plastics, and printing electronic circuits. The results of this project will enable rational design of mixing operations that exploit capillary forces to develop new materials. In multiphase suspensions containing particles and two immiscible liquids, capillary forces can induce particle clustering. The clusters comprise two or more particles bound by a meniscus liquid. In this project, the dynamics and rupture mechanics of particle clusters in simple shear or planar extensional flow fields will be studied using video microscopy and automated flow control. A feedback-controlled microfluidic device known as a Stokes trap will be used to precisely manipulate particles using viscous forces, to create well-defined meniscus-bound particle clusters, and to subject the clusters to precisely controlled flows. This work aims to achieve a fundamental understanding of the dynamics and rupture of particle clusters in well-defined flows. The project will reveal fundamentally new information, including the criteria for rupture of particle clusters, and how these criteria depend on the composition of the cluster, viscosity of the meniscus fluid, and particle roughness. Thedesign of mixing operations for liquid/liquid/particle mixtures is presently empirical in nature. This project will establish micromechanics-based design rules for such mixing operations that exploit capillary forces to develop new materials. The project will form the basis for training of graduate and undergraduate students. The two principal investigators will conduct numerous outreach activities at the undergraduate and pre-college level, including recruitment of underrepresented groups into their research groups, and mentorship of high-school students. 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.

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