Experimental assessment of the similarity law for a one-dimensional coupled heat and water vapor diffusion in hemp concrete

Similarity law is a mathematical mapping that aims to set up equivalences between different configura-tions regarding the involved physical parameters, space dimensions and the duration of the configuration. These equivalences are defined by means of the dimensionless formulation of the physical model that de-scribes a phenomenon. This concept is widely adopted in some scientific fields, notably in computational fluid dynamics. In heat and water vapor diffusion, similarities are applicable theoretically on configura-tions distinct in terms of material, space dimensions, duration or even imposed stress magnitude. It is worth noting that these are slow kinetic phenomena. In this regard, this study aims to verify similarities experimentally while using hemp concrete and reducing the duration of a reference experiment. Before performing measurements, two main limitations are fixed. First, by means of an experimental design, heat and moisture transfer are assumed one-dimensional. In addition, Dirichlet boundary conditions are considered at the surface that is exposed to ambient air. Mainly, temperature and relative humidity are measured at the quarter and middle of the material in order to compare the two similar configurations. Afterwards, an uncertainty study is carried out in order to discuss and justify the observed discrepancies. Following a deterministic approach, this investigation considers five sub-uncertainties which are related to : the calibration of used sensors, their positions, time of response, randomness of an experiment and the boundary condition modeling. Results show a good agreement between the reference and reduced configurations. Indeed, the discrepancies between both are entirely within the calculated confidence in-tervals. (c) 2023 Elsevier Ltd. All rights reserved.

Automated summary

Similarity law establishes equivalences between different configurations based on mathematical mapping and dimensionless formulation of the physical model. It is widely used in scientific fields like computational fluid dynamics. This study experimentally verifies similarities in heat and moisture transfer using hemp concrete and reducing the duration of a reference experiment. The results show good agreement between the reference and reduced configurations, with discrepancies within the calculated confidence intervals.