1. A FLUID DYNAMIC CONTROLLED DEVICE, COMPRISING: FLUID-STREAM-FORMING MEANS FOR FORMING A STREAM OF FLUID; FIRST BOUNDARY MEANS LATERALLY ADJACENT ONE SIDE OF SAID STREAM; SECOND BOUNDARY MEANS LATERALLY ADJACENT THE OTHER SIDE OF SAID STREAM, SAID SECOND BOUNDARY MEANS BEING GENERALLY OPPOSITE AND DOWNSTREAM OF SAID FIRST BOUNDARY MEANS; SEPARATING MEANS ADJACENT TO AND UPSTREAM OF SAID FIRST BOUNDARY MEANS FOR CREATING A PRESSURE GRADIENT ACROSS SAID STREAM IN A DIRECTION TO DEFLECT IT ONTO SAID FIRST BOUNDARY MEANS; AND VIBRATORY MEANS FOR DIRECTING A VIBRATORY FLOW OF FLUID AT SAID STREAM ADJACENT SAID SEPARATING MEANS TO DISTURB SAID STREAM IN SUCH A MANNER THAT THE PRESSURE ADJACENT SAID SECOND BOUNDARY MEANS IS REDUCED WHEREBY THE DIRECTION OF SAID PRESSURE GRADIENT IS REVERSED ACROSS SAID STREAM TO SWITCH SAID STREAM FROM SAID FIRST BOUNDARY MEANS TO SAID SECOND BOUNDARY MEANS.