抄録
Hydraulic properties are discussed of vortices separated at the edge of flat plate placed normally to the main
flow in a water flow tank. Visualized experiments on separation vortices show that the spin down of vortex
causes the upwelling of the bottom water.
We develop a theory on the generation period of the separation vortex and the upwelling velocity, based
upon the assumption that the kinetic energy loss of vortex due to spin down equals to the energy used to creat
the upwelling, and by using the boundary layer theory and the mixing length theory on turbulent flow.
Theoretical values of the circulation and generation period of vortex agreed well in good accuracy with
measured values. No upwelling velocity is measured directly because of technical difficulty. Instead of the upwelling velocity, its volume is measured. We estimated the volume of upwelling by measuring the changes of dye
concentration in the wake region behind the plate, since a part of bottom water in the wake is sucked up into the
vortices and resulting in the decrease of dye concentration.
