A series of experiments have been conducted in the stratified wind tunnel facility at the Environmental Flow Research Centre (EnFlo), University of Surrey, UK. The wind tunnel has a working section 20m long, 3.5m wide and 1.5m high. Stable boundary-layer flow over two-dimensional cosine-squared hills of differing slope have been investigated. One hill is of sufficiently steep slope to promote flow separation and recirculation whilst the other does not. Both hills are approximately 0.23m in height and occupy one quarter of the total boundary-layer depth.

Velocity measurements have been made across and downwind of the hills using two-component Laser Doppler Anemometry. When combined with a cold-wire probe an estimation of heat flux is possible. Pressure measurements have also been conducted across the centre line of the hills using a sensitive Barotron. Results highlight the evolution of turbulent stresses in response to the extra strain rates, both streamline curvature and acceleration, induced by the hill. The presentation will discuss results from experiments with both single hills of differeing slopes and multi-hill effects, where the upwind hill influences the flow and pressure fields of the downwind hill.