U.S. Army Corps of Engineers Bay Model

https://en.wikipedia.org/wiki/U.S._Army_Corps_of_Engineers_Bay_Model

by tosh • 2 months ago

235 63 2 months ago

en.wikipedia.org

WillAdams2• 2 months ago

It's a shame that there isn't a series of articles on such models --- saw the Chesapeake Bay model (mentioned in a footnote) on a field trip when I was much younger (and it was still in active use for research I believe, yes, as my kids constantly tell me, I'm old).

Simulation used to be essentially impossible, something one dreamed of, or had to pay for time on a Cray or similar supercomputer/cluster.

Apparently, the Chesapeake Bay model was built just as that was becoming feasible:

https://easternshorebrent.com/2017/11/30/doomed-progress-the...

and has since been dismantled and a business park built on the site.

DonHopkins3• 2 months ago

Ahoy crewmembers! Are you old enough to remember Captain Chesapeake and Mondy the Sea Monster?

Captain Chesapeake WBFF TV45

https://www.youtube.com/watch?v=a3kjJt_7zw4

Ahoy! - The Captain Chesapeake Story

https://www.youtube.com/watch?v=8QUGMVYIHvA

Did you know that Traffic Jam Jimmie was also Mondy the Sea Monster?!?

redm• 2 months ago

These are the kinds of interesting engineering challenges that were solved with human ingenuity and grit; I wish we were talking more about them to our youth to inspire imagination about what's possible.

nkrisc2• 2 months ago

The distortion is interesting and something I didn’t realize the model included. I assume that it’s necessary because the effects of surface tension and the viscosity of water (and other effects?) change its behavior at this scale relative to the features of the model?

WillAdams2• 2 months ago

Yes. Another technique was to use alcohol rather than water since it has lower surface tension, but that was only workable for smaller models (which were usually enclosed).

nkrisc2• 2 months ago

I think a model this size full of alcohol would also be quite hazardous for several reasons.

lorenzohess• 2 months ago

If I recall correctly, at an undistorted scale, the water would be so shallow that surface tension and viscosity would dominate, so the depths are exaggerated to keep the flow realistic.

More specifically, tidal flow obeys Froude similarity, not Reynolds. Matching the model's Froude number to the real Bay's requires enough depth for gravity waves and tides to scale correctly, which the vertical exaggeration provides.

But the distortion makes the flow too efficient, so copper strips are added throughout to achieve the right frictional resistance.

Gibbon1• 2 months ago

Triggered a memory. As I understand wind tunnel models often has bits of sand paper placed to generate turbulence at the right spots.

bumby4• 2 months ago

Have you ever watched a movie with a fire or explosion just didn't look right because it was a scale replica? At a subconscious level, you may have picked up on how the dynamics of the smoke or debris didn't fit right with the scale. It's because the fluids in the model lacked "similitude" at the adjusted scale.

When building scaled models, adjustments have to be made to create that similitude, usually done by comparing some dimensionless number at the real scale and model scale. If you're using water, maybe you can't adjust the viscosity, so you may you have to adjust the velocity to get the same dimensionless number. Everything doesn't just scale linearly; you tweak the variables to achieve the dimensionless value so the whole system dynamics remain faithful.

E.g.,

https://en.wikipedia.org/wiki/Froude_number

https://en.wikipedia.org/wiki/Rayleigh_number

contingencies3• 2 months ago

The fellow who lived next door to me told me of a similar model system used to model Sydney Harbour which he worked on in the 1970s. IIRC it was instrumented with electronics and linked to a VAX or similar early machine.

emmelaich3• 2 months ago

The Aus Navy had a computer simulation of Sydney Harbour, dating from the 70s or maybe 80s. One particular feature of the system was a disk drive about 1m in diameter with about 12 heads. Cost a bomb, but I guess it was worth it.

When I saw a demo, they had an easter egg of a Loch-Ness type monster in it.

There's also a topographical map of the harbour at St Ives showground but it's purely non-hydrographical. But it's almost disappeared now through neglect.

cucumber3732842• 2 months ago

The Aus Navy had a computer simulation of Sydney Harbour, dating from the 70s or maybe 80s. One particular feature of the system was a disk drive about 1m in diameter with about 12 heads. Cost a bomb, but I guess it was worth it.

Meanwhile the Soviets probably found a little inlet somewhere that was "close enough", evicted anyone who lived there and excavated it to match.

Some junior engineer probably had to wake up at 1am to take a kayak out to "Little Kotlin Island" to change the tape in the recording equipment in time for the tide change.

contingencies3• 2 months ago

Interesting about the St Ives showground map. Where is it exactly? They have a nice orchid show. Usually it seems to be mostly a bunch of HK dudes playing with RC cars.

LucasLanglois• 2 months ago

If you don't know Tom Scott, he has done a great video 4mn vide on the model where you can see it in action: https://www.youtube.com/watch?v=i70wkxmumAw

MontagFTB• 2 months ago

Yes, that’s a great video. The Mythbusters used the same model to understand Bay Area current flows during their Alcatraz escape attempt episode.

rbanffy2• 2 months ago

Someone should do a follow up episode with a person dressed up as Godzilla.

carderne• 2 months ago

John McPhee talks about a similar model for the Mississippi River in “The Control of Nature” Well worth a read. Fun stories about Hawaii and Los Angeles too, iirc.

Robdel12• 2 months ago

This is neat to see. US army crops of engineers is a negative “word” to me after growing up in FL and they destroyed so many ecosystems. And the entire Everglades. They’re still at it now. My family has basically spent the past 30 years fighting a ware they put in on our natural creek. It killed the creek, it shrunk the flow to the size of the culvert.

So, It’s neat to see something competent! Imagine if they modeled what cutting off the natural draining to the Everglades would do :p

bumby4• 2 months ago

It’s neat to see something competent!

The existence of negative externalities or tradeoffs does not inherently imply incompetence.

I remember reading that the USACE said the NOLA levees would not adequately protect against a category 5 hurricane but the powers that be didn’t think the added cost for a more robust design was worth the risk. If true, it doesn’t imply USACE was incompetent but that we live in an uncertain world with tough tradeoffs.

reaperducer• 2 months ago

US army crops of engineers is a negative “word” to me after growing up in FL

That you were able to grow up in Florida at all is largely because of the Army Corps of Engineers.

mattlong• 2 months ago

I highly recommend a visit. It’s only a beautiful ferry ride and nice walk along the waterfront away from San Francisco. A refreshingly retro and analog experience.

obvioustourist• 2 months ago

See also the Mississippi River Basin model built by German engineer POWs during WWII: https://en.wikipedia.org/wiki/Mississippi_River_Basin_Model

supertroop• 2 months ago

Don’t show something good the government has done or the POTUS will cancel it!!!

eezing• 2 months ago

This is a hidden gem in the Bay Area. Go check it out if you live near by.

youngtaff• 2 months ago

Why do the Army Corps of Engineers get so involved in civil infrastructure in the US - thinking of the Mississippi in particular?

In other countries the government would be involved but it would be a civilian rather than military role

bumby4• 2 months ago

Not sure about the exact thrust of your question but a few points:

- flood management is not easy to monetize so there is not much incentive for private industry. The timelines for design decisions (100 year, 500 year) often don’t mate well with private incentives

- it crosses many property boundaries which makes it hard to manage unless you have the rights of a government

- much of the work is still done by private companies but managed by the government, just like other infrastructure works like roads, bridges etc.

DonHopkins3• 2 months ago

Flood management in the Netherlands even influenced the country's style of government decision-making: the "Polder Model" of consensus-building.

The idea is that if everyone shares the same dikes and drainage systems, they have to cooperate regardless of political differences. A flood doesn't care whose land it is.

https://en.wikipedia.org/wiki/Polder_model

The polder model (Dutch: poldermodel) is a method of consensus decision-making, based on the Dutch version of consensus-based economic and social policymaking in the 1980s and 1990s. It gets its name from the Dutch word (polder) for tracts of land enclosed by dikes.

https://en.wikipedia.org/wiki/Maeslantkering

The Maeslantkering 'Maeslant barrier' is a storm surge barrier on the Nieuwe Waterweg, in South Holland, Netherlands. It was constructed from 1991 to 1997. As part of the Delta Works, the barrier responds to water level predictions calculated by a centralized computer system called BOS. It automatically closes when Rotterdam, especially the Port of Rotterdam, is threatened with flooding.

https://en.wikipedia.org/wiki/Delta_Works

The Delta Works (Dutch: Deltawerken) is a series of construction projects in the southwest of the Netherlands to protect a large area of land around the Rhine–Meuse–Scheldt delta from the sea. Constructed between 1954 and 1997, the works consist of dams, sluices, locks, dykes, levees, and storm surge barriers located in the provinces of South Holland and Zeeland.

wbl• 2 months ago

The US did not have a civilian engineering school for a few decades after the founding. West Point was the only institution creating engineers. Given they had responsibility for port defenses the civil engineering of waterways was an easy addition.

macintux• 2 months ago

https://en.wikipedia.org/wiki/United_States_Army_Corps_of_En... has a good overview. Note that 97% of the employees are civilians.

nxobject• 2 months ago

They're decentralized enough as well that some of their local offices have hilarious online presences. For example, Portland...

https://www.instagram.com/corpsofengineers_portland/

stevenwoo• 2 months ago

In addition to sibling comments for intent, the book Cadillac Desert documents how this government agency can be used to further moneyed interests, ie subsidize developments that would otherwise not be economically viable from local funding but become viable when federal taxpayer foots the bill. (The big examples in the book is building cities and farmland in deserts.)

gsquaredxc• 2 months ago

There's some good answers here but something important is missed. Militaries spend a lot of time having soldiers shoot rounds down the range to ensure everyone is up to snuff. The engineering corps is similar but better. You can fund target practice for your army engineers by having them go build public infrastructure. It's a win for the military (practical experience), win for locals (public infrastructure), and a win for the taxpayer (two for one deal).

bumby4• 2 months ago

I don't think that idea necessarily holds for the Army Corps of Engineers. They technically work under a military command, but the vast bulk of the engineers are civilians. The military officers tend to rotate in and out of positions relatively fast. And the civilians aren't required to do construction in combat theaters (although voluntary positions do exist). So the idea that the USACE is set up to give practice for military theaters isn't really apt. It's more about the scope and incentives of the projects they work on. E.g., a private company doesn't have the right timeline or profit incentives to build dams for flood control.

hirpslop• 2 months ago

The bay’s first LLM (large liquid model) was invented in the 1950s.

DonHopkins3• 2 months ago

Advection Is All You Need

On the Dangers of Stochastic Parrotfish: Can Large Liquid Models Understand the Bay?

The Brackish Lesson: Scale Beats Insight in Large Liquid Models

Large Liquid Models are Few-Drop Learners

Schooling Laws for Tidal Liquid Models

No Silver Mullet

e40• 2 months ago

Took my son there when he was young (6?) and we all loved it. What a great day trip.

msisk62• 2 months ago

I haven't been there in awhile.

Back in the 90's the Autodesk tech office was next door to the Bay Model and we'd occasionally pop over for lunch and tour the place.

Great to see it still around and open to the public.

dieselgate3• 2 months ago

Was it displayed at the Civic Center or did Autodesk have an office location in Sausalito? I had never heard of this Bay Model and believe to only have seen a model at the (new location) of the Exploratorium - this was over a decade ago so don't quite recall

hnav2• 2 months ago

Autodesk was founded in Marin and later moved down. This model is 10km^2 so it's not moving anywhere.

karlgkk• 2 months ago

I’d gone here as a young child in school, and then went as part of a team building afternoon. Massive Deja Vu in front of all of my coworkers

Lammy• 2 months ago

Big fan of this thing. It's one of my favorite places to take friends who visit the Bay Area.

Something that's not mentioned in the article is that the building they occupy is a former warehouse of Marinship, a World War Ⅱ shipyard that made Liberty Ships and T2 oil tankers used to supply fuel in the Pacific Theater: https://en.wikipedia.org/wiki/Marinship

The Bay Model building has a Marinship museum in a front room. For anyone who wants to see Marinship's full story in motion, here's my HEVC encode of ‘“Tanker” — 1942–1945 War Time History of Marinship Corporation’ https://mega dot nz/file/lgtmlKIA#asrzuwGOxi6l8I5BmgyAxfKkm1zFcxvY4SYS1SxqtZk

See also Marin City, which is the remains of Marinship's on-site worker housing: https://en.wikipedia.org/wiki/Marin_City,_California

e: the Bay Model building is the big square one that is center-frame starting at 04:30 in the video, Marin City at 09:23, and some beginnings of modern-day international oil politics at 12:28.

nonethewiser• 2 months ago

I went to SF once for a few days and this is one of the things my friend showed me in my limited time there. I remember it from time to time. It's pretty cool.

Im trying to reflect on why it was so memorable. I thought it was interesting at the time but it wasnt mind-blowing or something. I think it is just just such a unique oddity and a relic of the past. There was so much effort and space devoted to this. You'd never do something like that today.

Wistar• 2 months ago

I used to live in Tam Junction, close to Sausalito. I had lived there at least a year before I discovered the Bay Model and was amazed when I visited it. It is huge.

vlad-asis• 2 months ago

Their models HEC-HMS and HEC-RAS are really great hydraulic models. Unfortunately, with Windows native interfaces...

taco_emoji• 2 months ago

There's a similar model for the entire Great Lakes watershed at Discovery World in Milwaukee. You can even press a button to make it rain!

ThreatPortSec• 2 months ago

good

bigbrained124• 2 months ago

Did this use this to model operation sea-spray?

protocolture• 2 months ago

Everyone knows that Hydraulic models aren't for bays, they are for the British economy. https://en.wikipedia.org/wiki/Phillips_Machine

U.S. Army Corps of Engineers Bay Model

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