Open AccessSynthesis report on thermally driven coupled processes
Author(s) -
Ernest Hardin
Publication year - 1997
Language(s) - English
Resource type - Reports
DOI - 10.2172/16624
Subject(s) - matrix (chemical analysis) , boundary value problem , mechanics , conceptual model , fracture (geology) , experimental data , flow (mathematics) , thermal , statistical physics , flow properties , geology , geotechnical engineering , computer science , physics , mathematics , materials science , thermodynamics , mathematical analysis , statistics , database , composite material
The main purpose of this report is to document observations and data on thermally coupled processes for conditions that are expected to occur within and around a repository at Yucca Mountain. Some attempt is made to summarize values of properties (e.g., thermal properties, hydrologic properties) that can be measured in the laboratory on intact samples of the rock matrix. Variation of these properties with temperature, or with conditions likely to be encountered at elevated temperature in the host rock, is of particular interest. However, the main emphasis of this report is on direct observation of thermally coupled processes at various scales. Direct phenomenological observations are vitally important in developing and testing conceptual models. If the mathematical implementation of a conceptual model predicts a consequence that is not observed, either (1) the parameters or the boundary conditions used in the calculation are incorrect or (2) the conceptual basis of the model does not fit the experiment; in either case, the model must be revised. For example, the effective continuum model that has been used in thermohydrology studies combines matrix and fracture flow in a way that is equivalent to an assumption that water is imbibed instantaneously from fractures into adjacent, partially saturated matrix. Based on this approximation, the continuum-flow response that is analogous to fracture flow will not occur until the effective continuum is almost completely saturated. This approximation is not entirely consistent with some of the experimental data presented in this report. This report documents laboratory work and field studies undertaken in FY96 and FY97 to investigate thermally coupled processes such as heat pipes and fracture-matrix coupling. In addition, relevant activities from past years, and work undertaken outside the Yucca Mountain project are summarized and discussed. Natural and artificial analogs are also discussed to provide a convenient source of material documenting the conceptual and mathematical basis for modeling coupled phenomena. The actual models and codes, and their specific empirical and theoretical bases, will be documented in a separate report to be delivered in FY99