1993 年 13 巻 Supplement2 号 p. 75-78
It is said that the Joumon Age Culture continued 6, 000-7, 000 years since 9, 000 years ago, and the people who bore the culture is called Joumon-jin. Earthen ware that were produced by Joumon-jin are called Joumon-doki.
Joumon-doki have been discovered in various parts of Japan and there are many kinds of them. Among them, one discovered in Niigata District at the end of 1931 is very famous for its nice patterns, and it was named Kaen-doki.
The patterns on its lip and side wall are related to the water flow, the authers believe. The nice vortex patterns of Kaen-doki put on them were patterned after vortices that were observed downstream piles, rocks, etc. in a river as visualized by flowing leaves which played a role of tracer.
This fact was reproduced using the Floating Tracer Method, one of the visualization methods of modern age, and thus the process of vortex generation was cleared by utilizing the computer simulation.