Some researchers just like to make waves.
Posted on 08/22/2019 11:41:34 AM PDT by DUMBGRUNT
"Seeing the pictures appear on the computer screen was the best day at work I've ever had," says Simen Ådnøy Ellingsen, an associate professor at NTNU's Department of Energy and Process Engineering.
39 degrees It has long been assumed that the angle of the v-shaped wake behind a boat should always be just below 39 degrees, as long as the water isn't too shallow. Regardless whether it's behind a supertanker or a duck, this should always be true. Or not. For like so many accepted facts, this turns out to be wrong, or at least not always the case. Ellingsen showed this.
Boat wakes can actually have a completely different angle under certain circumstances, and can even be off-centered with respect to the direction of the boat.
(Excerpt) Read more at phys.org ...
This is an issue I pondered on during the many hours on aft watch.
Did you hear the one about the Austrailian physicists that decided they were going to solve the mystery one for all? They rented a boat, affixed it with video and other equipment to measure the angle of the bow wave. Then as they would move about at different speeds and in different conditions they’d have an undergraduate check the instruments every 5 minutes to see if the bow wave angle had changed. If it didn’t they (the PhDs) would open up some more beers.
Apparently they we hard at it till the grant money ran out two years and ten disgruntled undergraduates later.
That meme has a serious spelling error. It is “canna” not “cannot”.
This does seem counter-intuitive.
"Fuel consumption can double if the vessel is traveling downstream compared to upstream," Ellingsen said.
I suspect that is a serious oversimplification. They probably mean, fuel consumption per distance covered in the flow can be double when the vessel is traveling down stream instead of upstream.
Obviously, fuel consumption per distance referenced to fixed points, is less going downstream than upstream.
You can achieve infinite fuel consumption going upstream, simply by hold the speed of the boat in the flow to the speed of the current. From the bank, the boat will not be moving, but it will be consuming fuel.
Your fuel consumption going downstream can be zero, simply by turning off the engine. You still travel downstream, and do not consume fuel.
Nowhere does it explain how they came up with 39 degrees. And shouldn’t it be a function of the boat’s speed and shape?
The world may never know...
Some researchers just like to make waves.
Just two, but it's tough getting them in there.
“Physics Riddle” Q: How many theoretical physicists does it take to change a light bulb? A: Two. One to hold the bulb and one to rotate space.
Q: How many Germans does it take to change a light bulb?
A: One.
#GermansArentFunny
what if the lightbulb that needs changing is in France?
Running the bot in a tight cicle can make an incredibly huge boiling inner wake-tossed center. Lots of fun!
Good point!
Patriots need to be on their guard against politically correct “settled science.” This is same Democratic mentality as politically correct “established law,” laws wrongly legislated from the bench by activist judges.
I’ll have to inform my duck.
rwood
The wake you make falls mainly in the lake.
Buttermilk is actually rather good for the digestion, so he will neither f*rt nor sh*t out of season.
some people give the strangest excuses when caught watching porn at work...
Back about 1849 so scientist with time on his hands decided to show how a greenhouse works. He came up with his protocol ...and discovered that he didn’t know how a greenhouse works. Lately, at Harvard some scientists decided to see how nicotine addicts people. They found out that it doesn’t seem to be addictive as a chemical introduced into the human body at the sames percentages that smoking does it. So there ya go.
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