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### A Numerical Approach for Non-Linear Moisture Flow in Porous Materials with Account to Sorption Hysteresis

and Nyman, Ulf LU (2010) In Transport in Porous Media 84(3). p.735-754
Abstract
A numerical approach for moisture transport in porous materials like concrete is presented. The model considers mass balance equations for the vapour phase and the water phase in the material together with constitutive equations for the mass flows and for the exchange of mass between the two phases. History-dependent sorption behaviour is introduced by considering scanning curves between the bounding desorption and absorption curves. The method, therefore, makes it possible to calculate equilibrium water contents for arbitrary relative humidity variations at every material point considered. The scanning curves for different wetting and drying conditions are constructed by using third degree polynomial expressions. The three coefficients... (More)
A numerical approach for moisture transport in porous materials like concrete is presented. The model considers mass balance equations for the vapour phase and the water phase in the material together with constitutive equations for the mass flows and for the exchange of mass between the two phases. History-dependent sorption behaviour is introduced by considering scanning curves between the bounding desorption and absorption curves. The method, therefore, makes it possible to calculate equilibrium water contents for arbitrary relative humidity variations at every material point considered. The scanning curves for different wetting and drying conditions are constructed by using third degree polynomial expressions. The three coefficients describing the scanning curves is determined for each wetting and drying case by assuming a relation between the slope of boundary sorption curve and the scanning curve at the point where the moisture response enters the scanning domain. Furthermore, assuming that the slope of the scanning curve is the same as the boundary curve at the junction point, that is, at the point where the scanning curve hits the boundary curve once leaving the scanning domain, a complete cyclic behaviour can be considered. A finite element approach is described, which is capable of solving the non-linear coupled equation system. The numerical calculation is based on a Taylor expansion of the residual of the stated problem together with the establishment of a Newton-Raphson equilibrium iteration scheme within the time steps. Examples are presented illustrating the performance and potential of the model. Two different types of measurements on moisture content profiles in concrete are used to verify the relevance of the novel proposed model for moisture transport and sorption. It is shown that a good match between experimental results and model predictions can be obtained by fitting the included material constants and parameters. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Diffusion, Moisture, Sorption hysteresis, Transport model, Sorption, Finite elements, Numerical methods
in
Transport in Porous Media
volume
84
issue
3
pages
735 - 754
publisher
Kluwer
external identifiers
• wos:000281260000011
• scopus:77956011645
ISSN
0169-3913
DOI
10.1007/s11242-010-9538-3
language
English
LU publication?
yes
id
2805d4e6-4263-439d-95da-6fee3831cb7c (old id 1672566)
date added to LUP
2010-09-23 13:21:36
date last changed
2018-05-29 11:42:28
```@article{2805d4e6-4263-439d-95da-6fee3831cb7c,
abstract     = {A numerical approach for moisture transport in porous materials like concrete is presented. The model considers mass balance equations for the vapour phase and the water phase in the material together with constitutive equations for the mass flows and for the exchange of mass between the two phases. History-dependent sorption behaviour is introduced by considering scanning curves between the bounding desorption and absorption curves. The method, therefore, makes it possible to calculate equilibrium water contents for arbitrary relative humidity variations at every material point considered. The scanning curves for different wetting and drying conditions are constructed by using third degree polynomial expressions. The three coefficients describing the scanning curves is determined for each wetting and drying case by assuming a relation between the slope of boundary sorption curve and the scanning curve at the point where the moisture response enters the scanning domain. Furthermore, assuming that the slope of the scanning curve is the same as the boundary curve at the junction point, that is, at the point where the scanning curve hits the boundary curve once leaving the scanning domain, a complete cyclic behaviour can be considered. A finite element approach is described, which is capable of solving the non-linear coupled equation system. The numerical calculation is based on a Taylor expansion of the residual of the stated problem together with the establishment of a Newton-Raphson equilibrium iteration scheme within the time steps. Examples are presented illustrating the performance and potential of the model. Two different types of measurements on moisture content profiles in concrete are used to verify the relevance of the novel proposed model for moisture transport and sorption. It is shown that a good match between experimental results and model predictions can be obtained by fitting the included material constants and parameters.},
author       = {Johannesson, B. and Nyman, Ulf},
issn         = {0169-3913},
keyword      = {Diffusion,Moisture,Sorption hysteresis,Transport model,Sorption,Finite elements,Numerical methods},
language     = {eng},
number       = {3},
pages        = {735--754},
publisher    = {Kluwer},
series       = {Transport in Porous Media},
title        = {A Numerical Approach for Non-Linear Moisture Flow in Porous Materials with Account to Sorption Hysteresis},
url          = {http://dx.doi.org/10.1007/s11242-010-9538-3},
volume       = {84},
year         = {2010},
}

```