The use of ウ in these two cases to represent w is rare in modern Japanese except for Internet slang and customary transcription of the Latin sound [w] into katakana. E.g.: ミネルウァ (Mineruwa "Minerva", from Latin MINERVA[mɪˈnɛrwa]); ウゥルカーヌス (Wurukānusu "Vulcan", from Latin VVLCANVS, Vulcānus[wʊlˈkaːnʊs]). The wa-type of foreign sounds (as in watt or white) is usually transcribed to ワ (wa), while the wu-type (as in wood or woman) is usually to ウ (u) or ウー (ū).
Sometimes used in Japanese linguistics to transcribe the bidakuon [ja][ŋ] initial.
