Doctoral project: Numerical modelling of the coupled transfer of heat and mass in wood and engineering wood products

The objective of the project is to use advanced mathematical techniques to create a numerical tool governed by physical laws. The governing equations are capable of simulating the combined processes of moisture and heat transport in wood. The numerical model is created using the Finite Element Method (FEM). The model is useful in the prediction of moisture states and its effects on the physical and mechanical properties of wood materials.

Project information

Doctoral student
Winston Mmari
Björn Johannesson and Thomas K Bader, Linnaeus University
Project start
Nov 2017
Building technology (Department of Building Technology, Faculty of Technology)

More about the project

Wood and engineering wood-based products such as cross-laminated timber (CLT) are gaining increasing use in engineering, especially in building constructions. This is mainly due to the good strength and environmental friendliness of the new wood products. The material structure of wood, however, is heterogeneous and porous. This creates a high affinity of wood to moisture from the surrounding environment. The moisture in the wood material is greatly influenced by temperature (heat). Moisture is found in wood material in the form of water vapor in pores, bound water in the cell walls of wood and free water in the cavities of wood cells.

This doctoral project aims at using a multiscale, multi-component and thermodynamically consistent approach based on the hybrid mixture theory (HMT), to create a sophisticated non-linear and coupled transient numerical model by means of the finite element method (FEM). This modelling approach is defined by the principles of continuum mechanics and bounded by physical laws, and leads to a general FEM tool capable of simulating the combined processes of heat and moisture transfer and the related deformations.

The modelling aimed at in this project will improve the understanding of the underlying processes of moisture and heat transport and its interactions with wood. It will be applied to study the influence of moisture in the development of stresses and deformations of CLT elements. The model can also act as a baseline for providing some hints on how to plan and conduct additional in-depth experiments related to complex wood-moisture interactions. Practical applications of such a sophisticated model are feasible since it is implemented in the established FEM approach, and due to the currently fast growing computing power.

The doctoral project is part of the research field Cross-Laminated Timber (CLT) at the Department of Building Technology.