Abstract
Some important flow patterns in astatically stable fresh-salt water system were visualized using simple dye methods. Dye streak from a point source set up above interface of the flow system indicated a spiral pattern for high shear flow. This pattern means there occur coherent vortices caused by the internal shear instability. Visual observation shows that this instability effect extends to interface and constrains interfacial waves to generate. Line source by a dyed thread made it possible to visualize the three-dimensional stream structures in each layer and to obtain velocity profile from its time lines. Dyed thread mesh was successful in the observation of longitudinal vortices which play a very inportant role in the cause of the internal shear instability. Of all these visualizations Uranin was found the most. useful as dye material.
