EVOLUTION OF AIRCRAFT WEAKE VORTICES NEAR THE GROUND.

FEW STUDIES OF AIRCRAFT TRAILING VORTICES HAVE BEEN PERFORM ED IN SHEARED OR STRATIFIED FLOWS. YET, MEASUREMENTS INDICATE THAT THE ATMOSPHERE IS TYPICALLY BOTH SHEARED AND STRATIF IED. THIS LACK OF KNOWLEDGE COULD BE IMPORTANT IF VORTEX EVOLUTION IS SIGNIFICANTLY DIFFERENT IN SHEARED, STRATIFIE D FLOWS THAN IN THE UNSHEARED, UNSTRATIFIED FLOWS THAT HAVE BEEN STUDIED IN THE PAST. OUR RECENT LABORATORY AND NUMERICAL STUDIES INDICATE THAT THERE ARE SIGNIFICANT DIFFERENCES IN THE EVOLUTION OF A VORTEX PAIR WHEN TGE RICHARDSON NUMBER IS ON THE ORDER OF ONE OR LESS, I.E. WHEN THE SHEAR IS LARGE. THESE STUDIES WERE PERFORMED FOAR FROM SOLID WALLS. THIS PROPOSAL ADDRESSES THE PROPAGATION, PERSISTENCE, AND FATE OF AIRCRAT TRAILING VORTICES IN A SHEARED, STRATIFIED FLOW NEAR THE GROUND WHEN THE RICHARDSON NUMBER IS OF ORDER ONE OR LESS. THE OBJECTIVES OF PHASE I ARE TO DETERMINE WHETHER THESE FLOWS CAN BE STUDIED UNDER CONTROLLED, LABORA TORY CONDITIONS, TO DETERMINE WHETHER MEASUREMENTS CAN BE MADE OF SUFFICIENT QUALITY TO BE COMPARED TO PREDICITIONS FROM AL NUMERICAL COMPUTER CODE, AND TO ESTIMATE THE FREQUENCY AND LENGTH AND TIME SCALES OF THESE CONDITIONS IN THE ATMOSPHERE.