The effects of complexity, of simplicity and of scaling in thermal-hydraulics

• Published in: Nuclear engineering and design 2001-02, Vol.204 (1), p.1-27
• Main Author: Zuber, Novak
• Format: Article
• Language: English
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fluid mechanics; Heat transfer; Hydraulics; Installations for energy generation and conversion: thermal and electrical energy
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/S0029-5493(00)00324-1

This lecture has a twofold purpose. First, we will assess the state of the art and the trends in thermal-hydraulics (T-H) technology, within the context of replicating and non-replicating information systems. Four T-H examples are used to illustrate that an ever-increasing complexity in formulating and analyzing problems leads to inefficiency, obsolescence and evolutionary failure. By contrast, simplicity, which allows for parsimony, synthesis and clarity of information, ensures efficiency, survival and replication. This comparison (complexity versus simplicity) also provides the requirements and guidance for a success path in T-H development. The second objective of this paper is to demonstrate that scaling provides the means to process information in an efficient manner, as required by competitive (and, thereby, replicating) systems. To this end, the lecture summarizes the essential features of the Fractional Change, Scaling and Analysis approach, which offers a general paradigm for quantifying the effects that an agent of change has on a given information system. The paper will further demonstrate that a single concept and a single method may be used to scale and analyze all transport processes in a given field of interest (fluid mechanics, heat transfer, etc.) and/or across fields and disciplines (mechanics, biology, etc.) Therefore, the paradigm: (1) ensures economy and efficiency in addressing and resolving technical or scientific problems; and (2) enables a ‘cultural cross-pollination’ between different information systems (disciplines). By means of a simple example in the Appendix, we shall: (1) demonstrate the efficiency to be gained through scaling; and (2) illustrate the inefficiency and wastefulness of computer-based safety studies as presently conducted.