Three-Dimensional Mean Velocity Analysis of a 30 Degree Bend Flow

Abstract

The 3D velocity profiles of the 30° bend flow of Flack and Johnston have been analyzed in terms of the existing 3D turbulent boundary layer theories. Various cross-flow and near-wall similarity models were tested. Coles's cross-flow model described the velocity profiles satisfactorily. The wall function matched the data well, and the experimentally determined wake functions collapsed into a narrow band, which was however different from the originally suggested wake function. A new form of wake function has been proposed. Among the near-wall models, Hornung and Joubert's and Prahlad's models matched the data very well and excellent near-wall similarity from the wall to the boundary layer edge was achieved. This is rather unexpected in a 3D turbulent boundary layer flow with large skewing. The excellent performance of these two near-wall models could not be attributed to any particular reason.