Fluid Dynamics in Salt Lake City

I have blogged previously about attending the Joint Mathematics Meeting in San Diego (2018) for the first (and so far only) time, and the APS March Meeting in Las Vegas (2023), my fourth time attending that meeting.  I don't typically blog about the conferences I attend, but it behooves me to post today about one more, the APS Division of Fluid Dynamics annual meeting, which took place last week (Nov. 24-26) in Salt Lake City.  This is because fluid dynamics has been a central part of my scientific career, as well as a cornerstone of this blog.  Indeed, the Salt Lake City meeting was my sixth DFD.  My previous five have all been after I left graduate school:

• 2003:  Meadowlands, NJ.
• 2005:  Chicago, IL
• 2009:  Minneapolis, MN
• 2012:  San Diego, CA
• 2014:  San Francisco, CA

As can be seen, I had not attended DFD in exactly a decade.  Partly this is because I decided at the 2014 meeting that the APS March Meeting was probably of greater interest to me than a conference specialized in fluid mechanics, especially since the March Meeting had plenty of fluids sessions itself.  However, the March Meeting tends to be attended by physicists who do fluids; while DFD is dominated by engineers, applied mathematicians, and various Earth & planetary scientists who do fluids -- a much better representative group of this discipline. However I have found in my latter years that my interests in fluid mechanics tends towards historical, pedagogical, and foundational issues, rather than the cutting edge of research, which is what DFD showcases.  Nonetheless, attending DFD once a decade, while attending the March Meeting more often, may be quite appropriate in order to nourish my intellectual interests in physics and fluid mechanics.

Anyhow, this year's DFD was held at the Salt Palace convention center in downtown Salt Lake City.

The West Temple entrance to the Salt Palace Convention Center

I arrived on Saturday evening Nov. 23 to pick up my badge, but through a different entrance where a cheer-leading competition was taking place!  There was glitter all over the carpet, and children practicing their routines in the hallway.  I ran into a colleague in the hallway who must have seen my utterly bewildered expression, and he kindly directed me towards the DFD registration area.  Here is a shot of that part of the convention center at a calmer moment.

The DFD registration area at the Salt Palace Convention Center, as seen from near the West Temple entrance.

The meeting got going promptly at 8am Sunday morning, while the evening reception ran well into the night.  I don't think I headed back to my hotel until around 9pm that night, despite having forgotten that I had been given two free drink tickets for the reception.  (Thus I never used those tickets.)  The second morning session on Sunday featured a new "Interact" poster session, which began with one-minute flash talks by each poster presenter, followed by time for the audience to speak with the poster presenters one-on-one.  I attended the session on Rayleigh-Benard convection, which was graced by two top figures in the field:  Robert Ecke and K. R. Sreenivasan.  Unfortunately the latter's poster consisted of printouts of a recent paper published in the Journal of Fluid Mechanics, and the author did not stay very long, as I'm sure he had other people's posters in other sessions that he wanted to see.  Logistically, the flash talk portion of the session was difficult to execute gracefully, despite everyone's best efforts.  I'm not sure if this was much of an improvement over a regular poster session.

Hall C, where many of the plenary events, including the awards session, took place.

After lunch, the awards session took place in Hall C, presided over by this year's DFD chair, Peko Hosoi of MIT.  The reception, which was not a full scale banquet, took place in the exhibit hall (Hall A) at 7pm.

Entrance to Hall A, the exhibit area.

In the previous 5 DFD meetings, the reception included a real banquet.  Most memorable for me were the receptions for the 2003 and 2012 DFD meetings.  In 2003, the reception was held at Tavern on the Green, in Central Park of New York City.  Buses were provided to take us there.  I recall having conversations with Stephen W. Morris and (more briefly) Troy Shinbrot there.  At dinner I was seated with a professor and his wife, of Eastern European origin, whose names I cannot recall.  I remember the conversation turning toward the professor's son, who had pursued a non-lucrative career in avant-garde film-making.  Alas, the good professor appears to have been incredibly disappointed with his son's career choice.  He seemed to praise my contrasting choice to pursue a scientific career, albeit not one centered in academia, and not even closely related to fluid dynamics.  At the 2012 DFD reception, I befriended a French post-doc, and after dinner we went for a long walk along the marina, almost reaching the U.S.S. Midway, before turning back.  The post-doc had once worked for a technology start up, but their product, while technically quite innovative, provided only a marginal practical improvement over its existing competitors, and customers found it difficult to justify the cost (not just financial, but in requiring specialized training) to use the product.  It was a sound lesson in scientific entrepreneurship.  Eventually I began peppering him with questions about French politics and culture (this was the era of the presidencies of Monsieurs Sarkozy and Hollande).

Alas at this year's reception, I didn't have any interesting conversations at all.  I have also noticed across several conferences that I've attended this year that there are fewer exhibitors, especially book exhibitors.  Here, only SIAM and Cambridge University Press were purveying books (the latter was also promoting the Journal of Fluid Mechanics), while AIP Publishing and APS' Physical Review Fluids were hawking their journals.  I placed an order for two books with SIAM, and picked up a book (60% discount with reservation if picked up on site) from Cambridge, Joseph Powers' Mechanics of Fluids, which look to be very promising.  After returning home I placed an additional order for more Cambridge books, using the meeting 30% discount code.  I've felt for over a decade that they are the lead publisher in fluid mechanics, and I am pleased that they have not yet abandoned the conference circuit, though they may be feeling less and less competition these days.  JFM was celebrating its 1000th volume, and a commemorative brochure was distributed at the conference, which I think will be a lovely keepsake.  However, unlike the previous DFDs I've attended, there was no brochure prepared regarding the Gallery of Fluid Motion entrees.

Monday morning I mainly attended the Education and Outreach session, which featured many talks on in-class lab demos as well as alternatives to traditional textbooks.  I then attended the Fluids Education lunch, which was not clearly described ahead of time.  It turned out to be a panel discussion with lunch provided.  The table I sat at was not very talkative at all, so it wasn't a very social event, unlike the various mixers featured at other conferences I've attended this year.  Monday afternoon featured a poster session.  I zeroed in on one poster that was closely related to my graduate work from over 20 years ago, and while initially the presenters were absent, two of the authors eventually turned up, and I was able to talk to them.  There were also at least two rather controversial posters, which I will not discuss here, as they do not deserve any further attention.  (I am told that an ethics complaint was filed with APS regarding one of them.)

That evening, attendees were invited to visit the Leonardo Museum, a few blocks away, which currently has a major exhibit on flight, as well as smaller exhibits on AI, water, and a special exhibit related to the meeting, the Traveling Gallery of Fluid Motion (TGFM).  This is the second year of the TGFM, and this year's exhibit is titled "Spiraling Upwards".  For an additional $15, we could attend a private reception welcoming the TGFM, where the artists (one was a real artist, the others were DFD researchers) each gave a few words about their works.

The Leonardo Museum in Salt Lake City.

The Leonardo Museum was quite an appropriate venue for this event, as Leonardo DaVinci, its namesake, was a keen observer of fluid motion, and he rediscovered what we call the hydraulic continuity equation, a precursor of the mass balance principle in modern fluid dynamics.

I attended additional sessions on Tuesday, though I took a long lunch break to enjoy pho at a busy downtown eatery called Tamarind, which I highly recommend!

I've been away from physics and fluid mechanics for over two decades, so unlike conferences in my current field, where I constantly run into people I know, I am very much an outsider at the March Meeting and DFD conferences.  Indeed, I met only 3 people that I knew from before at this year's DFD, though I intend to reach out to a few others whom I met there and have some professional interests with.

The 2024 Nobel Prizes in science

DTLR cannot resist opining on this year's Nobel science prizes laureates, especially when several of the non-physics laureates have physics connections, while one of the physics laureates does not.

One of the two laureates for physiology or medicine is Gary Ruvkun, whose bachelor's and Ph.D. degrees are in biophysics.  One of the three laureates for chemistry, David Baker, had done a postdoc in biophysics.  He currently has an adjunct appointment in the physics department at his university, along with four other departments aside from his home department.  A second chemistry laureate, John Jumper, had done a bachelor's degree in physics and math, and a master's in theoretical condensed matter physics, before earning a second master's and a Ph.D. both in theoretical chemistry.

It is perhaps also notable that David Baker's father was a physicist and his mother was a geophysicist.  One of the physics laureates, John Hopfield, also had two physicist parents.  

Artificial intelligence was the center of this year's physics and chemistry awards.  Two of the three chemistry laureates were awarded for AI-based protein structure prediction, for their work with AlphaFold, which is owned by Google's parent company, Alphabet.  There is little doubt that this achievement belongs to biological chemistry.  I was pleased to see a share of the award go to employees of a private sector company instead of a university, not something that happens often nowadays.

The physics prize, however, has been extremely controversial, in many cases sparking outrage and cynicism, among both physicists and non-physicists.

Let's start with the laureates themselves before discussing their achievements.  A number of commentators, including some who should know better (e.g., Sabine Hossenfelder) falsely claim that the award was not given to physicists, but to computer scientists.  This is only half true.  One of the laureates, Geoffrey Hinton, is not a physicist, by either education or employment.  He is a cognitive scientist and computer scientist.  (Apparently he is also a direct descendent of George Boole!)  The other, John Hopfield, has superb physics bona fides.  His education was in physics, he was a Buckley Prize winner for his contributions to condensed matter physics, and he is probably the greatest living biological physicist today.  It is true that he is also considered a neuroscientist and a molecular biologist.  In fact, his last academic position before retirement was on the Princeton University molecular biology faculty.  He is a titan of both physics and interdisciplinary science, though the Nobel committee focused on his work on Hopfield Networks, a model of associative memory based on statistical physics (specifically, spin glasses).  He has served as President of the APS.

Unlike many, I celebrate Hopfield's Nobel award.  Geoffrey Hinton is really the puzzle here.  The Nobel committee zeroed in on his stochastic versions of Hopfield Networks, which are called Boltzmann machines.  However, his contributions to neural networks go well beyond that:  he introduced the backpropagation algorithm and later was one of the founders of deep learning methodology.  He is just as much a titan in the neural net community as Hopfield is in the biological physics community.

The history of neural networks is long, and boasts key contributions by a number of individuals.  While Hinton in undoubtedly a key figure in this history, others have also been recognized (including by the Turing award).  Perhaps the key point for the Nobel committee was Hinton's use of statistical physics ideas for the Boltzmann machine. 

There is no doubt that neural networks are used in physics, as in so many other fields of science and engineering.  There is also no doubt that ideas from physics have influenced neural network technology, and machine learning more generally.  But are Hopfield Networks and Boltzmann machines worthy of a Nobel Prize in physics?  This is a question that was hotly debated in the days after the awards were announced.  It seems though, the debate has been lopsided, at least in the sources I've read, with few commentators being willing to defend the Nobel commitee's choice this year.  This award was a huge surprise to nearly everyone who follows the Nobel Prize news every October, including me.  I was even more shocked when the host of the Physics World podcast admitted he had never heard of John Hopfield until the announcement of the prize.

The American Physical Society, in its official new release, decided to get behind the award, but notably emphasized Hopfield as a longtime member of the APS community.  This could be read as a veiled critique of Hinton's award; as far as I know, Hinton's one contribution to the physics literature is a co-authored paper that was published in a physics conference proceedings.

In principle there are several APS units that might choose to celebrate the award to either Hopfield or both Hopfield and Hinton:  the Division of Biological Physics, the Division on Computational Physics, the Topical Group on Statistical and Nonlinear Physics, the Topical Group on Data Science, and the Forum on Industrial and Applied Physics.  However, I have seen and heard of few who have actually embraced this year's award.

This is regrettable.  I think Hopfield is deserving of the honor in the sense that James Peebles was in 2019 - a kind of lifetime career recognition.  I'm not ready to render an opinion on Geoffrey Hinton's Nobel Prize in Physics.  We need to take a step back from the knee-jerk, immediate, and highly emotional reactions.  I'm hoping some thoughtful commentators will, in the coming year, weigh in with well considered opinions.  As a physicist who has worked in machine learning (there are now many, many of us), I may choose to view this award as recognition of those working in this interdisciplinary space who actually use physics ideas, regardless of our formal education or employment in physics.

Peer Review Week 2024

Apparently we are ending this year's "Peer Review Week".  Many publishers are celebrating the work of their peer reviewers, who are typically unpaid volunteers that support the review of articles submitted to academic journals, grants proposals submitted to funding agencies, and occasionally papers submitted for presentation at conferences.

For those of us who work in non-academic institutions, like private sector or government organizations, there is often a parallel internal peer review process for employees, before they are allowed to submit to an external journal or conference.  There are notable differences between this internal peer review process and the academic reviews I refer to above; the rest of this post will focus solely on the academic sector review.

Peer review has taken a great deal of criticism in recent years.  I personally am sympathetic to the view of Adam Mastroianni, who argues that no peer review is better than (at least conventional) peer review.  Post-publication peer review (such as on PubPeer) is, for me, a preferred way for a community to assess the merits of a scientific publication.  Peer review, as conventionally practiced, does not do what it claims to do, confer an imprimatur of quality and approval upon a scientific publication.  There is no limit to the stories of terrible papers published in top journals that contain almost blindingly obvious flaws, along with excellent papers that were repeatedly rejected by outstanding journals.  A defender of peer review may argue that surely the false positive and false negative error rates must be low.  It is impossible to verify such a claim because the peer review process is shrounded in anonymity, and publishers are reluctant to release any data regarding the performance of peer review at their journals.

I don't see anything of value that pre-publication peer review actually create that cannot be duplicated, in a better way, using post-publication peer review.

A thought-provoking podcast given by Dr. Mastroianni can be found at Econtalk (along with a reference to his substack article on the topic).  I won't rehearse all his criticisms here - he does it more eloquently than I could.

One issue not addressed by him is the inclusion of ad hominem attacks on the authors of manuscripts in reviewer reports.  The U.K.'s Institute of Physics Publishing (IOPP) released last week a campaign against such unprofessional comments in peer review.  This podcast is an extremely interesting discussion of the topic, and the proactive ways IOPP is using to address it.  IOPP also rates each review they receive, and is now willing to share this feedback with reviewers who request it.  It's about time someone reviewed the reviewers!  (I may well decide to take the peer review training course offered by IOPP if time allows.)

I've been on both sides of peer review on many occasions.  I've had experiences where the peer review process clearly improved my manuscript, and I've had experiences where the process clearly degraded the manuscript, that is, the published version is notably worse than the original, in my not-so-humble opinion.  I've experienced a few cases where reviewers of my work have signed their reviews, i.e., revealed their identities; most of the time they are anonymous, but in a handful of cases, I believed I could guess who some of them are.  

I've also heard from others who've had their ideas stolen by peer reviewers!

On the other hand, in my highly biased opinion, every peer review I have performed for others has resulted in improvements in their manuscripts.  It is notable that every article I have ever peer reviewed has eventually been accepted for publication.  On the other hand, I've never signed a review, so I've always been anonymous to the authors I've reviewed.

Finally, in a handful of cases I've posted non-anonymous post-publicaton peer reviews on PubPeer. And sometimes when I wonder about the legitimacy of a published paper, I'll check up on it in PubPeer.  I advise readers to do the same.

Hacking Google Scholar

Finally, we enjoyed (but were dismayed by) the account given on Reese Richardson's blog about how Google Scholar can be "hacked".  Phony papers are uploaded onto ResearchGate, to boost citations to one's own (possibly equally fraudulent) papers.  There are companies offering to carry out such a citation-boosting campaign for paying customers, but Richardson shows how easily one can do it oneself.  However after he wrote about it, Google Scholar removed the fraudulent citations to the work of "Larry Richardson" (a cat), without necessarily implementing a global solution to the problem.

Predatory conferences: an expose!

Also in this week's Nature, an investigation of predatory conferences!  Journalist Christine Ro actually attended one.  Her observations are eye opening.

I get spam emails from these conferences on a weekly basis.  I've never been tempted to attend one.  I tend to go to conferences sponsored by professional societies that I know fairly well, or other established conference series.  However, as the article shows, many do not have the luxury of being as picky as I am.  Predatory conferences are basically rip-offs, of both the attendees and those who evaluate their CVs.

DTLR hereby denounces predatory conferences, and urges scientists to boycott these sham events.

More Earth Science

The June issue of Physics Today featured an interesting article by Gayen and Klocker, "Deep Convection Drives Oceanic Overturning", pointing to the inadequacy of the classical Rayleigh-Benard model of ocean convection.  This reinforces my questioning of the sincerity of those who study small aspect ratio thermal convection, when they make claims that their research is somehow relevant to real convection in planetary or stellar environments.

This month's Eos has a really nice summary of the flaws of the Colorado River Compact, by Ge et al.  Although I don't live in the Colorado River catchment, I am not far away, and this is a case study of the inevitably ugly collision of science and politics.

Speaking of which, this week Nature has a news article by Jeff Tollefson on a whistle-blower at the U.S. Geological Survey.  Unfortunately, any government bureau is necessarily politically accountable, and this leads to unavoidable clashes betweeen scientific "experts" and political authorities.  Formal whistleblower protections codified in federal law have little or no actual value in the real world. though federal employees are forced to take annual trainings on them.  It is a colossal deceit.

An Antarctic expedition

I would also like to strongly recommend a delightful article by a journalist (Sofia Moutinho) who joined a scientific expedition to Antarctica, described in the June issue of Eos.  As someone who does not routinely do field work, this piece was an intriguing glimpse at the intense tempo of operations, and extreme conditions, for such an expedition.