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The purpose of this paper is to numerically investigate the flow characteristics and extend the data of friction factor and Reynolds number product of hydrodynamically developing laminar flow in three-dimensional rectangular microchannels with different aspect ratios.

Using a finite-volume approach, the friction factor characteristics of Newtonian fluid in three-dimensional rectangular ducts with aspect ratios from 0.1 to 1 are conducted numerically under no-slip boundary conditions. A simple model that approximately predicts the apparent friction factor and Reynolds number product f_appRe is referenced as a semi-theoretical fundamental analysis for numerical simulations.

The accurate and reliable results of f_appRe are obtained, which are compared with classic numerical data and experimental data, and the simple semi-theoretical model used and all comparisons show good agreement. Among them, the maximum relative error with the classic numerical data is less than 3.9 per cent. The data of f_appRe are significantly extended to other different aspect ratios and the novel values of f_appRe are presented in the tables. The characteristics of f_appRe are analyzed as a function of a non-dimensional axial distance and the aspect ratios. A more effective and accurate fourth-order fitting equation for the Hagenbach's factor of rectangular channels is proposed.

From the reliable data, it is shown that the values of f_appRe and the model can be references of pressure drop and friction factor for developing laminar flow in rectangular channels for researchers and engineering applications.

This paper aims to examine a copy Hiraga Gennai wrote advertising the toothpowder brand Sosekiko in terms of its target audience, product decisions pertaining to branding and packaging, pricing and advertising objectives and message appeals. A masterless samurai in the eighteenth century, Hiraga Gennai is considered Japan’s first advertising copywriter. Life of the versatile Renaissance man Gennai and the influences of his accomplishments on advertising in following generations are briefly discussed.

The research draws from a sampling of classical and contemporary literature as well as the interpretation of the images shown here. Visual content is described and analyzed as well.

Gennai’s witty and humorous advertising copy for handbills attracted the townspeople of Edo. The toothpowder market was mature and competitive, and Gennai’s copy emphasized differentiation through packaging and volume discount rather than ingredients. The advertising copy has culturally unique aspect: It appeals to the audience’s ninjo, or feelings of humanity, and explicitly solicited disseminating positive word-of-mouth by the audience.

This research shows that activities resembling more contemporary marketing practices, such as advertising and branding, for consumer products such as toothpowder existed in eighteenth-century Japan, more than a century prior to the paradigmatic development of marketing concept. The possibility for Gennai as a potential strategic marketing planner and implementer, in addition to advertising copywriter, is researched and analyzed.