Ship Model Scaling: The IMPOSSIBLE Dream

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Күн бұрын

Пікірлер: 26

@___Chris___ 4 жыл бұрын

On a different subject: Everybody is talking about bow design, but I imagine the stern is just as important. Could you make an episode about different stern/transom shapes, stern waves and advantages/disadvantages of different shapes and how they relate to planing/displacement/semi-displacement hulls? I'm not only thinking about pitch stability but also speed and efficiency.

@DatawaveMarineSolutions 4 жыл бұрын

Excellent idea. I will add it to the list.

@justin.s9783 4 жыл бұрын

I been looking at the best way to go from a drawing to a scale model . I don't have 50k for a tow tank test , but i would like to see if my design is worth it. Good vid

@spacemansabs 4 жыл бұрын

could you make a video on the most basic shapes of ships compared to more complex shapes? simple totally convex everywhere racing kayak compared to big wave tankers or that new zumwalt navy ship?

@branislavbabic4579 2 жыл бұрын

It is obvious that you are naval architect, you have beard in shape of anchor :-) Great video, bravo!

@Zarcondeegrissom 3 жыл бұрын

noctua probably could have used this vid as an example when trying to explain why an 80mm fan can't just be 'resized' up to 120mm or 140mm in size without it changing the performance of the fan, lol. I understood the reasons why it doesn't work, I just wasn't able to figure out a way to describe it to people that know nothing about fluid dynamics and just want a quiet computer to play games on. yes, even air has surface tension not just sound wave velocities and fluid flow stuff, so it is a very similar issue for resizing fans. (I think it was Noctua, may have been Cooler Master regarding larger versions of the 212 cooler. I think that was at CES 2019, tho I'm not sure)

@VictorGomes1 3 жыл бұрын

This is good!!!

@Tophatmetalgear Жыл бұрын

Gracias

@akoponen 4 жыл бұрын

Since the Froude scale uses momentum and gravity and one finds it hard to scale gravity, how about changing the momentum...say by varying the density or viscosity by using a fluid like oil, mercury or alcohol? Probably cheaper than building a spinning circular room with a tank that circles the walls and can handle high centrifugal forces (AKA artificial gravity). But both should be doable. Not sure that having a water tank on a vomit comet (for low gravity) would work for long enough to get good results.

@DatawaveMarineSolutions 4 жыл бұрын

Good idea. Unfortunately, water is fairly unique. It has one of the lowest viscosities of any fluid out there, proportional to momentum. And to solve the scaling problem, we need to get less viscosity. So that doesn't leave much room to improve without getting into really expensive or really toxic fluids. mercury is a good example. Technically less kinematic viscosity than water, but I would never want to see a giant pool of it. That's how things go with engineering. Quite often, we find that mathematics on paper are safer and far more practical than inventing new experiments.

@akoponen 4 жыл бұрын

@@DatawaveMarineSolutions Wouldn't plotting the results with various other fluids (plural) help in extrapolating the information that you are really seeking?

@weatheranddarkness 4 жыл бұрын

Is surface tension a major concern in scaling of froude number? Clearly at Very small speeds and scales it's a very strong influence on dynamics, how is it treated in a towing tank environment?

@DatawaveMarineSolutions 4 жыл бұрын

For most experiments in the towing tank, we can ignore surface tension. Most towing tank models are around 1 - 4 m. in length. At that size, surface tension does not really contribute to the model physics.

@weatheranddarkness 4 жыл бұрын

@@DatawaveMarineSolutions good to know

@nicholasgoodfellow5774 Жыл бұрын

How small did you think they modeled ?

@ChristianNally Жыл бұрын

What about simulation? Presumably when one simulates a boat within a computer, it could give comparable results to a small physical model? Is that the cheaper/easier way to design larger ships? What software are people using for this?

@DatawaveMarineSolutions Жыл бұрын

Yes, simulation is a good alternative to model testing. When we use simulation, we typically model the ship at full scale, to avoid these scaling issues. The computer doesn't care about the physical size. Is it cheaper? There is considerable debate about this. It typically depends on the number of tests needed in the towing tank. If you need a lot of tests, simulation is usually cheaper. As to software: ANSYS CFX, Siemens StarCCM+, Simerics, OpenFOAM, MSC Cradle CFD. All the big software packages get used in the marine industry.

@Zigge 4 жыл бұрын

Would another fluid than water work as a model scale fluid?

@DatawaveMarineSolutions 4 жыл бұрын

We have looked into it. Unfortunately, to get any improvement from the current situation, you would need a fluid with less viscosity than water. And water is already one of the least viscous fluids in existence. If I were to search the entire realm of chemistry, I could probably find a few fluids that have less viscosity than water. But then there are the practical matters. We need something that is relatively cheap (since we will fill a swimming pool with it), it needs to remain stable over a long time (we rarely change the water in a towing tank), and it needs to be relatively safe to handle. Combine all those criteria, and no one has yet found anything better than water.

@weatheranddarkness 3 жыл бұрын

Alcohol is used for special effects because it behaves similar to water at a smaller scale. But then filling a pool with alcohol has loads of issues.

@isairuelas 3 жыл бұрын

Es necesario medir el tiempo a escala? Tiempo real del bote podria desacelerarse

@DatawaveMarineSolutions 3 жыл бұрын

Yes, time also changes from model scale to full scale ships. This is most important when showing videos of models. The towing tank will slow down the video to match actual performance at full scale. Side note: this is also a trick Hollywood uses when showing something like a reservoir flooding a canyon. They will construct a model and flood the model, but playback the video at a reduced speed. It can look just like real life.