In 1752 , a French mathematician called Jean le Rond d’Alembert proposed a paradox . He said that an ideal physical object with a free - slick Earth’s surface would have a drag of zero when moving through a liquid . Proving it has been a bit more hard , but a novel written report is close to an resolution .
conduct by the King Abdullah University of Science and Technology in Saudi Arabia , scientists have found a way to make a house of cards around an object that dramatically abbreviate the retarding force as it fall through H2O . The findings are release inScience Advances .
The study involved drop two 2 - centimetre - wide-cut lump into water . One was ignite to a very high temperature , about 400 ° C ( 750 ° F ) , while the water was fire up to 95 ° C ( 200 ° fluorine ) . The second testicle was coated in a superhydrophobic coating , one that repels water , and send away into water at room temperature .
In both experiments , the researchers find oneself that the drag on the ball could be dilute by up to 90 percent using these methods . Although it ’s not completely drag free , it ’s a major step in that commission .
“ In the field of fluid dynamic , we ’ve always used a supposed sphere because we have n’t been able-bodied to create an aim with a gratuitous - pillowcase surface – until now , ” say Dr Evert Klaseboer of the Institute of High Performance Computing , one of the work ’s co - authors , in astatement .
“ It could become a schoolbook example of some fundamental hydrodynamic theories . ”
In the first experiment using temperature , the ball directly boiled the water as it entered the liquidity . This create a static level of water vapour around the orchis , encasing it in gas and reducing the puff .
The 2d experiment is perhaps more appealing , as it worked at elbow room temperature . Using a spraying - on piss repellent commonly used for side mirror on gondola , it was able-bodied to hold a alike layer of gas between the ball and the body of water , again dramatically reduce the drag .
standardized engineering have been employ before in thing like supercavitating torpedoes , which utilize a bubble of steam to cut back hide clash drag and permit the torpedo to pass speeds of more than 400 kilometers per hour ( 250 mile per hour ) .
However , these can only reduce drag by 10 to 20 per centum . A 90 percent reduction , as attain in this study , is a important melioration . Time will differentiate what practical applications this has , but we ’re sure d’Alembert would be impressed .
