Measured Reynolds Stress Tensors in a Three-Dimensional Turbulent Boundary Layer

T boundary-layer solution techniques for three-dimensional flows have been slow in evolving. The principal difficulties center around questions of the adequacy of the empirical modeling of the turbulent or Reynolds stresses necessary in the computer solution of such flows. Such models include the empiricism of mixing length, eddy viscosity, or turbulent stress-turbulent energy transport equation relationships. Reynolds stress measurements can be very useful in verification of these empirical models. The measurement of all six unknown elements of the Reynolds stress tensor, however, is a significantly difficult undertaking requiring substantial equipment, the development of a technique, and in some cases substantial data reduction. An extensive experimental investigation is reported in which all six unknown elements of the Reynolds stress tensor as well as the mean velocity field were measured through a pressuredriven, three-dimensional, turbulent boundary layer with moderate skewing relative to the freestream direction. The turbulent stresses were measured by the rotating probe technique. Two measured turbulent shear stresses and the mean velocity field data are compared with values obtained from a numerical solution for the boundary-layer flow. There is moderate-to-good agreement between the measured values and those computed for an isotropic mixing length model.