# University of Minnesota

Aerospace Engineering and Mechanics

**Fall 1996 Seminar Series**

*Three Dimensional Turbulent Boundary Layer Over a
Swept Bump*

## Dr. Donald Webster

__Abstract__

The imposition of mean flow three dimensionality on a turbulent boundary
layer has usually been coupled with relatively strong streamwise pressure
gradients in previous experiments. Such pressure gradients can cause reductions
in the vertical turbulent mixing usually attributed to three dimensionality.
Control experiments in which the same streamwise pressure gradient is applied to
both a 2D and a 3D turbulent boundary layer are not available. The goal of this
work is to develop a three dimensional turbulent boundary layer (3DTBL)
experiment which has an obvious 2DTBL analog. The geometry chosen is the flow
over a surface mounted bump swept at a 45 degree angle. The analog, of course,
is an unswept bump with the same streamwise cross-sectional profile. Mean
velocity and turbulent stress profiles were measured at several locations above
and downstream of the bump. The relative effects due to surface curvature,
streamwise pressure gradient, and mean cross-flow are compared for the two
cases. Of particular interest is the vertical turbulent mixing and relative
alignment of the shear stress and strain rate vectors. Also of interest is the
effect of Reynolds number on a 3DTBL. An unique wind tunnel design allowing Re
to be varied by an order of magnitude will be presented.

###
Friday, October 4, 1996

209 Akerman Hall, 2:30 - 3:30 p.m.

#### Refreshments served after each seminar in
227
AKERMAN HALL .

Disability accommodations provided upon request.

Contact
Leslie Petrus : Secretarial Assistant.

*petrus@aem.umn.edu* (612) 625-8000.