Kolosov was assigned to AHL Lehigh Valley on Wednesday, Jordan Hall of NBC Sports Philadelphia reports.
The Flyers elected to carry three goaltenders for several weeks while Kolosov was on the roster, but the 23-year-old hasn't appeared in a game since Jan. 2. He hasn't been particularly sharp over 15 appearances with Philadelphia this year, posting a 4-8-1 record, 3.45 GAA and .870 save percentage. Kolosov should have more consistent opportunities to play while he's in the minors.