Structure of the Stratified Flow over Three-dimensional Ridges

An experimental study has been made of the stably stratified flow over three-dimensional ridges. The ridge models are triangular in cross-section and the aspect ratios of the cross-stream width of the ridge to its height were changed from 2 to 6. The experiments were performed by towing models through linearly stratified saline-water solutions. The Froude number Fr (=U sub(0)/NH) was changed from 0.05 to 1.66 (and arrow left ), where U sub(0) is the towing speed, N the Brunt-Vaeisaelae frequency and H the height of models. The streamline patterns around models were visualized by means of the neutrally buoyant tracer particles suspended in the working fluid. The dividing-streamline heights at the windward side of the models were measured from the streamline patterns. The velocity fields at several vertical cross sections were obtained by the PIV method. The structure of the flow over the ridge model is basically depending on the Froude number. The aspect ratio of the model has a negligible effect on the flow patterns over the model. The dividing-streamline height at the region near the edge of the model is, however, a little larger than that at the center of the model. Moreover, the dividing-streamline height for a ridge model is a little smaller than that for a circular cone model.