The Science of Ship Design


>>DESIGNING SOMETHING LIKE THE HULL OF A SHIP CAN BE AN EXPENSIVE PROCESS. SO HOW DO YOU RIGOROUSLY TEST OUT A DESIGN BEFORE YOU EVEN BUILD IT? A UNIQUE RESEARCH PROGRAM AT THE UNIVERSITY OF IOWA MAKES THAT POSSIBLE, USING SOPHISTICATED SOFTWARE, MODEL SHIPS, AND AN ENORMOUS INDOOR POOL. PROFESSOR FRED STERN LEADS THE UNIVERSITY OF IOWA’S SHIP-HYDRODYNAMICS PROGRAM, THE HOME OF THIS HIGH-TECH FACILITY.>>THESE ARE CALLED WAVE BASINS. YOU CAN SEE THE WAVE-MAKERS AT THE FAR END HERE. THEY’RE PLUNGER TYPE. THEY GO UP AND DOWN. THEY GENERATE EITHER REGULAR OR IRREGULAR WAVES IN THE BASIN. THE NEXT PART FOR US, THEN, IS THE CARRIAGE. THIS IS A CUSTOM-DESIGNED CARRIAGE. IT FOLLOWS THE MODEL. THERE’S TARGETS ON THE MODEL THAT THE CAMERAS AND THE TRACKING SYSTEM USE. OURS IS UNIQUE INSOFAR AS IT’S DESIGNED SPECIFICALLY TO CARRY MEASUREMENT SYSTEMS TO MEASURE THE LOCAL FLOWS AROUND THE FREE-RUNNING MODELS.>>BELIEVE IT OR NOT, THIS NEARLY $5 MILLION FACILITY WAS DESIGNED AND BUILT PRIMARILY FOR THE PURPOSE OF VALIDATING OR TESTING COMPUTER CODE. THAT CODE, CFDSHIP-IOWA, IS A SIMULATION SOFTWARE DEVELOPED AT THE UNIVERSITY OF IOWA FOR THE OFFICE OF NAVAL RESEARCH. IN THE PAST, STERN AND HIS RESEARCH TEAM VALIDATED THE CODE BY RUNNING THEIR MODELS IN A 300-FOOT-LONG TOWING TANK, BUT AS COMPUTER POWER GREW AND THE CODE BECAME ABLE TO DO MORE ADVANCED SIMULATIONS, SO IT REQUIRED A MORE SOPHISTICATED TOOL FOR VALIDATING.>>OUR CODES DEVELOPED VERY RAPIDLY OVER THE LAST, REALLY, 5 TO 10 YEARS, TO THE POINT THAT WE’RE ABLE TO PREDICT THE EXACT TRAJECTORY OF THE MODEL, INCLUDING RUDDERS AND ROTATING PROPELLERS, AND NO LONGER RESTRICTED TO CAPTIVE SIMULATIONS. THEREFORE, TO VALIDATE IT, WE NEEDED TO SEE, “WELL, HOW ACCURATE WOULD THE TRAJECTORIES BE?” BY TRAJECTORIES, I MEAN MODELS. FOR EXAMPLE, YOU START OUT STRAIGHT AHEAD, YOU GIVE THE RUDDER A 35-DEGREE ANGLE, AND IT’S GONNA GO IN A CIRCLE. WE WANT TO KNOW, WHAT’S THE RADIUS OF THAT CIRCLE? ANOTHER TYPE IS A ZIGZAG TEST WHERE YOU PUT THE RUDDER 10, 10, 20, 20, AND THEN YOU PREDICT WHAT’S KNOWN AS THE OVERSHOOT. THERE’S HALF A DOZEN OR SO OF THESE TRADITIONAL TESTS, BOTH IN CALM WATER AND WAVES, THAT SHIPS HAVE TO BE ABLE TO DEMONSTRATE THE CAPABILITY OF PERFORMING TO A SATISFACTORY STANDARD IN ORDER TO BE BUILT. AND SO OUR FOCUS IS NOT ACTUALLY DESIGN. OUR FOCUS IS DEVELOPMENT OF THE TOOLS.>>WHILE THE WAVE BASIN WILL ENABLE NEW ADVANCES IN HYDRODYNAMICS, PROFESSOR STERN SAYS IT INDICATES THE DIRECTION MUCH OF SCIENCE IS ALREADY HEADING.>>YOU KNOW, THE FUTURE OF ENGINEERING IS SIMULATION-BASED DESIGN, AND, IN FACT, WE CAN SIMULATE THINGS WE CAN’T MEASURE. SO YOU BEGIN TO SEE A MAJOR SHIFT IN THE SCIENTIFIC METHOD, WHERE WE WENT FROM ARISTOTLE, OKAY, WHO BASED EVERYTHING ON LOGIC — HE DIDN’T BOTHER TO — YOU KNOW, HE THOUGHT MEN AND WOMAN HAD A DIFFERENT NUMBER OF TEETH IN THEIR MOUTHS. IT’S ONE OF MY FAVORITE STORIES. OF COURSE, THEY DON’T, AND HE COULD HAVE FIGURED THAT OUT EASILY BY JUST LOOKING IN HIS WIFE’S MOUTH, BUT — THEY’RE TEETH. BUT, NO. SOME LOGIC AND NO VALIDATION. GALILEO SAID, “OKAY, VALIDATION. EXPERIMENTS. PHYSICAL OBSERVATIONS.” BUT THERE’S LIMITS THERE, TOO. NOW WE COME BACK TO, IF YOU THINK OF SIMULATION TECHNOLOGY AS REALLY LOGIC, SO NOW WE’RE COMING BACK TO LOGIC — LOGIC, THOUGH, COUPLED WITH THE EXPERIMENTS. THIS IS THE ENGINE OF SIMULATION-BASED DESIGN, AND, IN THAT SENSE, EACH OF THESE STEPS ARE JUST LITTLE, YOU KNOW, STEPS ALONG THE WAY. WE’LL ALWAYS NEED THE SMALLER FACILITIES, THE MEDIUM-SIZE, AND THE LARGER FACILITIES. THIS FACILITY IS HALF THE SIZE IT SHOULD BE FOR ACTUAL INDUSTRIAL USE, BUT FOR BASIC SCIENCE, IT’S JUST PERFECT.>>TO LEARN MORE ABOUT SHIP HYDRODYNAMICS AND THE SCIENCE OF ALL THINGS FLUID, VISIT…

18 comments

  • posro1988

    zumwalt class FTW!

    Reply
  • Estevan Sanz

    I've been researching into building boats and found an awesome website at Denelle boat builder (google it if you're interested)

    Reply
  • Niroj Shrestha

    There are many factors in creating an amazing design. One resource I discovered which succeeds in merging these is the Denelle Boat Builder (google it if you're interested) without a doubt the best info i've heard of. look at this interesting site.

    Reply
  • Niroj Shrestha

    There are many factors in creating an amazing design. One resource I discovered which succeeds in merging these is the Denelle Boat Builder (google it if you're interested) without a doubt the best info i've heard of. look at this interesting site.

    Reply
  • SANDEEP SHARMA

    If the ship is destroyed.
    Ideas of saving

    Reply
  • Muhammad Chaldun

    Excellent

    Reply
  • Gerry

    Take a bow, Mr Stern !

    Reply
  • Evelyn Lokko

    ????????

    Reply
  • Carmel Pule'

    Oh, come on, I come from a family of boat builders since 1708 and humans have been building ships and boats for so long that most characteristics are well known, be the centre of gravity below or above the centre of buoyancy. Stability is a well defined state. As for the run along the ships and what causes broaching as was shown at 2:25 well, any designer with experience will have it in him to get very close to the desired performance. Even the curves at the bows and the aft run so that the propellers will not have a differential pressure across their disc area can be approached and curve fitting with the minimum rate of changes can be optically guessed for their lowest rate of changes hence the pressure distributions along the hull of any ship.
    It is nice to have all those facilities, but my forefathers came up with good shapes in their wooden traditional boats and you know when I look at the best in modern design including the America's cup contenders, the superyachts and other seacraft, well traditional fishing boats were not too bad, The Cutty Sark and the Blue Nose did not go through tank testing and believe me their hulls still competes with the best these days. I admit that modern materials as carbon fibres and lightness have made planing hulls with lighter materials but again the shape required for any performance is still in the bones of a good designer and he knows when to truncate the transom so that the water will not curl around it to cause a low pressure and slow the boat down at the back end due to the low pressure generated by a lifted transom, a good designer would know when and when not to make a straight run at the back. Really all one needs to do is to look at the shape of birds and fish and they tell the whole story of what is required for any occasion.
    Birds and fish with their wings and fins, had developed the wing and fin tips far ahead of anyone who had a test tank and it is surprising how the wing tips of propellers took so long in being shaped like those on birds and fish. As yet, no one has copied the fins and tails of dolphins and whales where all the fins have their tips with both the leading edge and trailing edge trailing back for that is what the water dynamics around the propeller tips demand.
    I designed boats and propellers and all turned up fine, but the secret is that before anyone decides to build boats, aircraft and propellers one need to walk to the coast and the countryside and have a good look at what nature produced if one wants a craft that is economic in its shape and travels at convenient speeds with the most efficient manner. If one can afford the power and what goes with it, any shape will do, as if one is still worried about the shape, just never mind, put it on hydrofoils and let it go above the waves and one would not need to hustle too much about design. Look at the America's cup and the sailing hyrofoils the latter reaching more than 60 knots. So , experience and a feel for the behaviour of water does help a lot more than what people think. Still it is a modern world but I predict that all software algorithms and their models will not reach the processing of an experienced human mind. The computers may be faster control system than the human mind and so for control purposes it is good to have fast computers to control fast crafts in land sea and air, but for creating concepts and a feel for what they can do, I do conclude that the human mind can still hold it position.

    Reply
  • Tubmaster 5000

    They build ships in Iowa??

    Reply
  • Justin Frias

    This is cool

    Reply
  • Espen Krogh

    Great! Looking forward to hear your speech about Integrated High-Fidelity Validation Experiments and LES for a Surface-Piercing Truncated Cylinder at Straight Ahead Without and With Sway Motion at NTNU Trondheim, Norway today

    Reply
  • Henry Mayhew

    I think that tank is in fact big enough. Maybe he should make smaller models if he is not satisfied.

    Reply
  • Randy39761

    Fred stern works with ship….im done lol

    Reply
  • Cody Nemo

    How did i end up with a ship design software validation project and basically an advert for the design software?
    Probably because i was watching videos on engineering, and videos on ships.
    The youtube algorythm is pretty good as long as google doesn't deliberately mess with it.

    Reply
  • ice fox

    Can anyone help me? I'm a graduating Naval Architect student and we're having our thesis now. The thing is i had many ideas but my teacher assesed it and mostly of them relate to ship but are not naval architect design related.. Can anyone suggest or share something good for a thesis project? Please and thankyou

    Reply
  • Nikko Bryan Fiedalan

    if only our university have research facilities like this 🙁

    Reply
  • Jacob Kareem

    i loved this and when am older i love to design ships!

    Reply

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