Chris Johnson

96 posts

Chris Johnson

Chris Johnson

@grainsandfluids

Reader in Nonlinear Dynamics at the University of Manchester. Interested in a wide range of granular and fluid flows.

Manchester, England Katılım Ağustos 2014
108 Takip Edilen151 Takipçiler
Chris Johnson
Chris Johnson@grainsandfluids·
@UoMpodcast Is there a problem with permissions on the podcasting system? My teaching videos (embedded) now show a permission error, and when logged into video.manchester.ac.uk I get the following when trying to watch my own videos (while logged in)
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Oliver Jensen
Oliver Jensen@oeskildjensen·
Exploring links between Marangoni spreading, optimal transport and Suminagashi, in the Journal of Fluid Mechanics at bit.ly/44ka7FM
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Chris Johnson
Chris Johnson@grainsandfluids·
@mpaldridge I think ⁴⁺⁴⁺⁴⁺³ / ₈ is allowed, though that may be too specific, given other rhythms in the melody
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Matthew Aldridge
Matthew Aldridge@mpaldridge·
@grainsandfluids I really want to say the second bar is in 7½ / 4 (or maybe 3¾ / 2 ?), but I’m not sure that's allowed…
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Matthew Aldridge
Matthew Aldridge@mpaldridge·
What’s the time signature of the new Thom Yorke jazz-instrumental thing, then? (I hear it as a bar of 6/4 followed by a bar of 15/8, I think.) youtube.com/watch?v=OJpAf8…
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Chris Johnson
Chris Johnson@grainsandfluids·
@mpaldridge I'd maybe say 3/2 not 6/4 - it feels like simple not compound time.
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Chris Johnson
Chris Johnson@grainsandfluids·
Four years after this visit, the 'future developments' have come to fruition and are published in JGR Atmospheres — "Modelling Wind-blown Umbrella Clouds in Lagrangian Dispersion Models" doi.org/10.1029/2023JD… , led by my student @frank_millward . @MetOffice_Sci @UoMSciEng
Chris Johnson@grainsandfluids

Just returned from a great few days at the @metoffice_sci learning about their atmospheric dispersion modelling and discussing future developments, as part of the @NERCscience 'V-PLUS' project. Many thanks to @claireswitham and the rest of the ADAQ team for their hospitality.

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Chris Johnson
Chris Johnson@grainsandfluids·
Postdoc position in debris flow dynamics available at Manchester - details at jobs.manchester.ac.uk/Job/JobDetail?… , application deadline 31st August. This project combines modelling, field observations at Illgraben, and small-scale lab experiments — something for everyone!
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Chris Johnson
Chris Johnson@grainsandfluids·
@mpaldridge I think the short answer is no, not many. Gell-Man–Low theorem and Barndorff-Nielsen–Shephard model are two others, but neither sprang to mind...
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Matthew Aldridge
Matthew Aldridge@mpaldridge·
@grainsandfluids Are there many examples of this? (Birch–Swinnerton-Dyer is the only one that comes to mind.)
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Matthew Aldridge
Matthew Aldridge@mpaldridge·
(I’d been looking for this for a while, but could never remember the correct combination of names to Google in order to find it.)
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Chris Johnson
Chris Johnson@grainsandfluids·
@mpaldridge I think my take on this is similar to the Oxford comma: comma iff any of the items contains 'and'; en-dash iff any of the names is double-barrelled.
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Matthew Aldridge
Matthew Aldridge@mpaldridge·
Also, I’d have done these as en-dashes rather than hyphens, tbqh
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Dr Fabian Wadsworth
Dr Fabian Wadsworth@WadsworthFabian·
Here's a new analytical solution for projectile motion in the case of a vertical launch (i.e. projectile thrown straight up), including drag forces. I'm excited about this because it could be used to more easily invert for source parameters from volcanic eruption videography.
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Chris Johnson
Chris Johnson@grainsandfluids·
@mpaldridge I'd actually notate this as a metric modulation (<crotchet>=<dotted crotchet>) rather than tempo change at your 3/4 bar. The tempi don't quite work perfectly (82bpm to 126bpm in the recording is a factor of 1.53 not 1.5), but I suspect ×1.5 was intended.
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Chris Johnson
Chris Johnson@grainsandfluids·
@mpaldridge I don't think that's a defence, because the notes in question (green=yours, red=theirs) don't cross a change in tempo. Their version would imply that there is a steady triplet beat from their first 2/4 bar up to their 𝅘𝅥 =125, which is not true...
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Chris Johnson
Chris Johnson@grainsandfluids·
🚨Postdoc available! A three-year @NERCscience funded postdoc on modelling debris flow dynamics will be available at the University of Manchester @UoMSciEng, starting early 2023. ⭐️Please RT and pass on this early announcement to potential candidates. DM/email me for details.
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Chris Johnson retweetledi
Detlef Lohse
Detlef Lohse@detlef_lohse·
#EFMC14: Anne Juel from Manchester, giving her plenary lecture on instabilities and pattern formation in viscous fingering: A fresh dynamical system theory view on a classical problem and variations thereof (elastic walls, modified cross-sections).
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Chris Johnson
Chris Johnson@grainsandfluids·
@nbehera2022 I'll post the job advertisement on twitter when it comes out, or email me if you'd like more information
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Chris Johnson
Chris Johnson@grainsandfluids·
@davepetley FYI, we've just had a project funded on modelling exactly this type of debris flow, focusing on surge waves at Illgraben. Postdoc announcement at twitter.com/grainsandfluid…
Chris Johnson@grainsandfluids

🚨Postdoc available! A three-year @NERCscience funded postdoc on modelling debris flow dynamics will be available at the University of Manchester @UoMSciEng, starting early 2023. ⭐️Please RT and pass on this early announcement to potential candidates. DM/email me for details.

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Dave Petley
Dave Petley@davepetley·
A rather splendid, large debris flow in the famous Illgraben catchment in Switzerland. Watch to the end to see a large pulse travel through the system.
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Keşfet

@oeskildjensen @amandaghassaei @mpaldridge @frank_millward @MetOffice_Sci @UoMSciEng @WadsworthFabian @LMU_Volc