抄録
Meaning of similarity is discussed from rather wide point of view that is from philosophical point it is recognized as a useful tool of recognition. Symbol is considered a unification of a similarity of an object and some representative of it, which is used by human being. In fluid mechanics discovery of novel similarity law means always new development of the research. Law of the wall is one of the cornerstone of such a similarity laws and the log law contained it is the impressible law for every one who learns turbulence at the first time. While which can be derived from various methods and confirmed from very many experiments, but questions about its validity are raised by some researches. Very active controversy on it appeared in recent years by famous scholars. In this report, a personal over view of the history of the law will be given and some comments are presented for the future development of it.
