A Review of Scaling Theory for Hardware Models and Application to an Urban Dew Model

Abstract

Scale modeling is of interest to physical geographers because it may permit physical systems to be reduced in complexity and size. However, for modeling results to have general applicability, formal scaling criteria must be met. This paper reviews scaling theory for hardware models for physical geographers, especially those interested in micro-and urban climates, and out-of-doors models. Criteria addressed dealt with physical domains (i.e., space, time, and temperature fields), physical processes such as radiation, conduction and convection, and discrete enclosures such as buildings. To demonstrate how theory can inform design, a case study is presented: the 1/8-scale, out-of-doors model constructed by the author to study urban dew. Dew deposition is temperature driven so, in this case, surface temperatures in the model needed to duplicate those seen at the full scale in real time. This was achieved using the Internal Thermal Mass (ITM) approach, wherein the thermal inertia of each scaled building was inflated by adding bottled water. Scaling criteria were also used to specify the layout, materials of construction and vegetation characteristics in the model, and the street-canyon length required to simulate an extensive urban neighborhood