1 9 5 8 ) ▁ ▁References ▁ ▁External ▁links ▁ ▁Category : 1 8 9 2 ▁birth s ▁Category : 1 9 7 5 ▁death s ▁Category : Ital ian ▁cinemat ograph ers <0x0A> </s> ▁In ▁fluid ▁dynamics , ▁Dar win ▁dr ift ▁refers ▁to ▁the ▁phenomen on ▁that ▁a ▁fluid ▁par cel ▁is ▁perman ently ▁disp la ced ▁after ▁the ▁passage ▁of ▁a ▁body ▁through ▁a ▁fluid ▁– ▁the ▁fluid ▁being ▁at ▁rest ▁far ▁away ▁from ▁the ▁body . ▁ ▁Consider ▁a ▁plane ▁of ▁fluid ▁parc els ▁per pend icular ▁to ▁the ▁direction ▁of ▁the ▁body ' s ▁constant ▁velocity ▁vector , ▁far ▁before ▁the ▁passage ▁of ▁the ▁body . ▁During ▁the ▁passage ▁of ▁the ▁body ▁the ▁fluid ▁parc els ▁move , ▁according ▁to ▁their ▁L agr ang ian ▁motion . ▁Far ▁after ▁the ▁passage ▁of ▁the ▁body , ▁the ▁fluid ▁parc els ▁are ▁perman ently ▁disp la ced . ▁The ▁volume ▁between ▁the ▁initial ▁plane ▁of ▁the ▁fluid ▁parc els ▁and ▁the ▁surface ▁consisting ▁of ▁the ▁par cel ▁positions ▁long ▁after ▁the ▁body ' s ▁passage ▁is ▁called ▁the ▁Dar win ▁dr ift ▁volume . ▁ ▁The ▁phenomen on ▁is ▁named ▁after ▁Sir ▁Charles ▁Gal ton ▁Dar win , ▁who ▁proved ▁in ▁ 1 9 5 3 ▁that ▁the ▁dr ift ▁volume ▁multip lied ▁with ▁the ▁fluid ▁density ▁equals ▁the ▁added ▁mass ▁of ▁the ▁body , ▁– ▁known ▁as ▁Dar win ' s ▁theorem . ▁ ▁As ▁shown ▁by ▁E ames ▁and ▁Mc Int y re ▁in ▁ 1 9