video: We discover that S. cerevisiae (baker's yeast) growing on a viscous liquid behave like "active matter": They metabolically generate fluid flows many times larger than their unperturbed colony expansion speed, and that flow, in turn, can dramatically impact the colony growth and morphology. We show that yeast cells generate fluid flows by consuming surrounding nutrients and decreasing the local substrate density. This leads to misaligned fluid pressure and density contours in the colony vicinity that ultimately generates convection. As the viscosity of the substrate is lowered and the self-induced flow intensifies, we observe three distinct morphologies: At the highest viscosity, cell proliferation and movement produces compact circular colonies; intermediate viscosities give rise to compact colonies with unusual "fingers" that break into smaller cell clusters; at the lowest viscosity, the expanding colony fractures into many mutually repelling fragments that can colonize an entire 94-mm-diameter Petri dish within 36 hours. view more
Credit: Severine Atis, University of Chicago and Harvard University Bryan T. Weinstein, Harvard University Andrew W. Murray, Harvard University David R. Nelson, Harvard University
VIRTUAL MEETING (CST), November 24, 2020 -- The American Physical Society's Division of Fluid Dynamics (DFD) is pleased to announce the award-winning posters and videos of the 38th Annual Gallery of Fluid Motion. A highlight of the annual DFD meeting since 1987, the Gallery illustrates the science--and very often also the beauty--of fluid motion.
"Submissions covered a wide spectrum of phenomena, as usual, from turbulent mixing flows to the shapes and dynamics of floating microbial environments," said Saverio Spagnolie, an associate professor of mathematics at the University of Wisconsin-Madison who organized the Gallery with colleagues David Richter (University of Notre Dame) and Ken Kiger (University of Maryland).
"But this year's submissions also included a substantial number of videos and posters devoted to the spread of COVID-19 through speaking, coughing, and sneezing, and the hydrodynamics of mask usage. It was encouraging to see how the community as a whole remains resilient to the current challenges, and how important the research being done by its members can be to general human health and prosperity," said Spagnolie.
"Since its inception, the Gallery has been a highly competitive venue for new and compelling presentations at the intersection of art and science," said Kiger, Keystone Professor in Maryland's department of mechanical engineering.
An esteemed panel evaluated dozens of entries for their striking visual qualities and scientific interest. Outstanding posters will be recognized and displayed at the 2021 APS March Meeting meeting and published in the September 2021 issue of Physical Review Fluids.
"Even in the virtual format, the flow physics exposed visually in our Gallery of Fluid Motion is a cornerstone of this meeting," said Jonathan Freund, Willett Professor and head of aerospace engineering at the University of Illinois Urbana-Champaign and chair of the DFD2020 meeting.
The top prizes in each category are named for the late Stanford University fluid mechanics professor Milton Van Dyke, whose "An Album of Fluid Motion" has inspired researchers in the field for decades.
Milton Van Dyke Award Videos Winners
V0020: Rocket Yeast
V0052: Impact of high-speed diesel drop trains - pursuing cleaner diesel engines
V0067: Air flows in opera
Milton Van Dyke Award Poster Winners
P0004: Spectral Landscapes of Flow Instabilities in Brain Aneurysms
P0017: Fluid Dynamics of COVID-19 Spread
P0027: Viscous wrinkling of non-uniform sheets
Gallery of Fluid Motion Winners
V0026: Direct fuel injection effects in a supersonic cavity flameholder
V0019: Rayleigh-Taylor Instability in Drop Impact Experiments
V0074: The beauty of turbulent convection: a particle tracking endeavor
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All videos and posters are available at https://gfm.aps.org/ and licensed under the Creative Commons Attribution-NonCommercial 4.0 International License. Any reuse must credit the author(s) and provide a link back to the individual entry page.
ABOUT DFD
The Division of Fluid Dynamics of the American Physical Society, established in 1947, exists for the advancement and diffusion of knowledge of the physics of fluids with special emphasis on the dynamical theories of the liquid, plastic and gaseous states of matter under all conditions of temperature and pressure. For more information about DFD, visit https://www.aps.org/units/dfd/.
ABOUT APS
The American Physical Society (APS) is a nonprofit membership organization working to advance and diffuse the knowledge of physics through its outstanding research journals, scientific meetings, and education, outreach, advocacy, and international activities. APS represents over 55,000 members, including physicists in academia, national laboratories, and industry in the United States and throughout the world. Society offices are located in College Park, Maryland (Headquarters), Ridge, New York, and Washington, DC.