Numerical Prediction Model for Fungal Growth Coupled with Hygrothermal Transfer in Building Materials

Abstract

A mathematical model that reproduces fungal proliferation and morphological colony formation was developed on the basis of a reaction diffusion modelling approach. In this modelling, fungal life stage was separated into two, active and inactive stage, and it was assumed that active fungus moves by diffusion and reaction while generating and producing inactive fungus. The effects of temperature and humidity on fungal growth were explicitly incorporated in the reaction term of nutrient consumption/production of active fungus in this governing equation. The damping function, which reproduces the effects of temperature and humidity on fungal growth, was developed and explicitly based on the fungal index proposed by K. Abe. In order to estimate the sensitivity of the proposed numerical fungal growth model, fungal growth on the surface of building materials was analysed for four types of building materials, and the prediction results were compared with the results of WUFI-Bio and the fungal index.

Integrated Numerical Simulation with Fungal Spore Deposition and Subsequent Fungal Growth on Bathroom Wall Surface

“…In our previous study, the damping function (T, ') was expressed according to the isopleth diagrams of fungal index proposed by Abe [26]; this was incorporated into the reaction together with the terms relating to the generation of active fungi and the effect indirectly influences fungal diffusion. The prediction accuracy of our proposed model and numerical approach were validated by WUFI-Bio model and Fungal Index as proposed by Abe [11].…”

“…In the field of life sciences and biology, the basic concept of proliferation or morphological growth can be formulated as mathematical models, and mathematical and theoretical approaches using computer simulation to understand these phenomena have developed into the fields known as mathematical biology and theoretical biology. We have already proposed morphological fungal colony formation model on building materials based on reaction diffusion approach [9,11]. This model has potential and possibility to predict precisely the fungal morphological contamination in indoors.…”

“…Concerning the impact of temperature and humidity effects on fungal growth, we have already reported the coupled simulation method of reaction-diffusion model for fungal growth prediction and hygrothermal transfer in building materials [11]; in which the damping function of fungal growth as a function of temperature T and relative humidity ' was proposed. In our previous study, the damping function (T, ') was expressed according to the isopleth diagrams of fungal index proposed by Abe [26]; this was incorporated into the reaction together with the terms relating to the generation of active fungi and the effect indirectly influences fungal diffusion.…”

“…Numerical simulation for 336 h was reasonable enough for fungal growth prediction, but a long-term analysis of the order of year would be needed for the evaluation and assessment of the fungal contamination. reaction diffusion model for fungal growth adopted in this analysis, the predicted growth speed of this model was adjusted to agree with the prediction results of WUFI-Bio developed by Sedlbauer [24] for spore germination and subsequent hyphal growth speed [11]. In this analysis, effective nutrients for fungi were present on the masonry joints and the surface nutrient concentration of tiles was assumed to be zero; hence, the active fungi (u) avoided the surface of tiles and grew on the joints between tiles.…”

“…Concerning the fungal growth prediction, a mathematical model has been developed and is being proposed by the authors that would reproduce fungal proliferation and morphological colony formation on two-dimensional wall surfaces. The reported coupled analytical procedure for the simulation would be integrated with consideration of hygrothermal transfer inside building materials [9][10][11].…”