Watch the latest #KITP Blackboard Lunch talk by Karen Daniels (NC State) —
Rigidity (or not) on the Earth's surface and beyond
24.02.2026 17:30
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Watch the latest #KITP Blackboard Lunch talk by Karen Daniels (NC State) —
Rigidity (or not) on the Earth's surface and beyond
It took me quite some time, but the article following a talk at the DFD 2024 is finally online! Clogging is widespread, but the associated physics remains poorly understood. I am trying to give a (biased) view and some general knowledge here: doi.org/10.1103/rfk8...
Our new paper, led by @ramsudhirsharma.bsky.social (with Alexandre Leonelli, Kevin Zhao, Eckart Meiburg), has been published in @apsphysics.bsky.social PRL. We revisit hourglasses/silos and ask what really sets the discharge rate. See more here: doi.org/10.1103/3g2f-nslz
3D printing meets fluid mechanics! Thrilled to see our Annual Review of Fluid Mechanics article on direct-ink writing featured by @utknoxville.bsky.social. With Brett Compton & @raytyler.bsky.social : tickle.utk.edu/mae/news/com... @annualreviews.bsky.social @univofmaryland.bsky.social
🚨 POSTDOC OPENING 🚨
NIH-funded Bio-Fluid Mechanics Postdoc in my lab @univmiami.bsky.social
Hofstenia miamia | cilia-driven flows | behavior & neuroscience
Collab w/ Mansi Srivastava @harvard.edu
🕒 Start: Jan–Feb 2026
⏳ 1 yr, renewable | Email me ASAP!
#Postdoc #Biophysics #FluidDynamics
I am looking to hire a postdoc to work with me on fluid-structure interactions in complex and active fluids. Ideally the candidate will have a strong background in numerical/asymptotic analysis and fluid mechanics (complex fluids / LCs even better).
www.mathjobs.org/jobs/list/26...
I am looking to hire PhD students to join our Multiphase & Multiscale Flow Lab in Mechanical Engineering @univofmaryland.bsky.social
Background in ME, Physics, ChemE, Civil (or related), interest in fluid mechanics/soft matter, and hands-on lab work are key.
Please help spread the word!
Looking forward to being @upenn.edu tomorrow for the 26th Mid-Atlantic Soft Matter Workshop. I’ll share some of our recent work on granular materials, with results from @ramsudhirsharma.bsky.social, @sreeramr.bsky.social and others in the group!
The Fudge Lab at Chapman University is recruiting a postdoc for an NSF-funded project on the biophysics of hagfish defensive slime deployment. Please repost!
Apply here: tinyurl.com/4p937dn5
We highlight some DIW challenges related to fluid mechanics and soft matter, such as extrudability and clogging, filament stability, post-deposition spreading, slumping, and buckling. Hopefully, it will inspire various fundamental studies in fluid mechanics. (including by us)
Thrilled that our article in @annualreviews.bsky.social
of Fluid Mechanics is out! “Fluid Mechanics Challenges in Direct‑Ink‑Writing Additive Manufacturing” doi.org/10.1146/annu.... I am grateful to the two co-authors, @raytyler.bsky.social and Brett Compton. @univofmaryland.bsky.social
New @univofmaryland.bsky.social article about our NSF project on sediment flows with Eckart Meiburg @ucsbengineering.bsky.social me.umd.edu/news/story/s.... Thrilled to see the project featured and excited to get started.
Take‑home. Very small holes clog; below ~3 grain diameters there’s no flow, and around 3–6 it’s intermittent. Large holes act like dense, fluid‑like jets with a steady rate. This is also why hourglasses keep time so well. @univofmaryland.bsky.social @ucsbengineering.bsky.social [4/4]
Why openings matter. Near the edge, grains dilate in a thin boundary layer. This boundary layer only extends 10–15 grain diameters, but it changes the discharge rate. Once you account for it, all the data collapse onto a single curve! [3/4]
What we find. We split the flow rate in two: the speed of the grains and how they pack at the opening. Gravity and the hole size set the speed. Away from the rim, packing settles to a near‑universal “free‑fall” value. We show this with 3D experiments and DEM simulations. [2/4]
Excited to share our new preprint on the discharge of granular materials from a silo. Led by @ramsudhirsharma.bsky.social , we went after a simple question: What is the flow rate through the opening? The answer turns out to be "simple" and quite general. See more here: arxiv.org/abs/2509.14415 [1/4]
The GRFP lives!! (due end of October)
www.nsf.gov/funding/oppo...
Excited to share that our NSF PMP project with Eckart Meiburg has been funded! We’ll study cohesive immersed granular flows through experiments and simulations to improve predictions of sediment transport & slurry processing. @univofmaryland.bsky.social @ucsbengineering.bsky.social
Check out the @kitp-ucsb.bsky.social conference we're (Vashan Wright, Sujit Datta, Nathalie Vriend) organizing:
www.kitp.ucsb.edu/activities/s... for THIS JANUARY 6-9!
Geoscientists, physicists and engineers: are you intellectually adventurous and been wondering "is this all there is?" 🧪
Our new study from Joanne Steiner’s PhD work and with C. Morize, P. Gondret, and I. Delbende has just been published in Phys. Rev. Fluids! We study vortex rings generated when a disk moves toward or away from a wall. doi.org/10.1103/ynxr...
Excited to be an invited speaker in EP018: Geophysical Granular Flows & Sediment Transport at AGU 2025 (Dec 15–19)! I’ll be sharing our results on cohesive granular materials. Many thanks to the organizers!
Abstract submissions open until July 30. agu.confex.com/agu/agu25/pr... @agu.org
We are grateful to receive funding from the ACS PRF to investigate how fibers and anisotropic particles reorient, bend, and sometimes clog in porous media. From microplastic transport to fiber-laden inks, we aim to uncover the physics behind their transport through experiments and modeling.
Congrats to all the new Fellows! It’s quite an impressive cohort
5/ Read more :
🔗 Popular science article FR : www.espci.psl.eu/fr/actualite...
🔗 Full publication in PNAS: www.pnas.org/doi/10.1073/...
And a video entry to the Gallery of Fluid Motion at the APS DFD 2023: www.youtube.com/watch?v=V0RJ...
And bonus: the winning entry from @ramrajesh97 to the Gallery of Soft Matter @apsdsoft.bsky.social last year that shows some cool pictures with fiber suspensions
Capillary flows of particulate suspensions are already complex, but anisotropic fibers add even more layers of complexity. We are excited to further explore fiber dynamics in various situations. Feedback and suggestions are very welcome!
#3: Fiber coverage becomes uneven when increasing the volume fraction of fibers. Increased fiber overlap at higher concentrations reduces coating uniformity, despite fibers maintaining an isotropic orientation.
#2: Higher Weber numbers and increased fiber fractions enhance splashing events. We map this splash/no-splash transition.
#1: Increasing fiber concentration significantly reduces droplet spreading due to higher effective viscosity. Our findings extend existing spreading models of suspensions of spherical particles to account for fiber suspensions explicitly.