10th U6+ Consortium of African Universities International Conference

Forest canopies regulate atmospheric airflow, turbulence, heat transfer, moisture transport and carbon dioxide exchange, thereby influencing local climate. However, accurately representing canopy–atmosphere interactions remain challenging because of vegetation drag and turbulent mixing. Mathematical modelling based on the Navier–Stokes equations provide a physically consistent framework for analyzing these processes. This study developed a Navier–Stokes- based mathematical model to investigate airflow within forest canopies and evaluate its influence on momentum transfer, turbulence generation, heat transport, moisture transport and carbon dioxide exchange. Computational Fluid Dynamics (CFD) approach based on the Reynolds- Averaged Navier–Stokes (RANS) equations coupled with the standard k–ε turbulence model was employed. Vegetation effects were represented using a canopy drag-force parameterization based on leaf area density. Transport equations for temperature, water vapour and carbon dioxide were solved alongside the momentum equations. The governing equations were discretized using the Finite Volume Method (FVM) and solved numerically in MATLAB for dense, medium and sparse canopy configurations. Air velocity increased with height in all canopy configurations but remained lowest in dense canopies because of stronger vegetation drag. Turbulent kinetic energy reached its maximum near the canopy top, indicating enhanced shear-induced turbulence. Temperature increased from approximately 298 K near the forest floor to about 303 K above the canopy. Moisture and carbon dioxide concentrations decreased with height owing to increased turbulent mixing, while dense canopies retained higher moisture and carbon dioxide levels than medium and sparse canopies. Forest canopy density significantly controls airflow attenuation, turbulence intensity and scalar transport. Dense canopies enhance micro-climatic regulation through greater momentum reduction, moisture conservation and carbon retention, whereas sparse canopies promote stronger atmospheric mixing. The developed modelling framework provides a robust numerical tool for investigating forest–atmosphere interactions and supporting climate, environmental and ecosystem management studies.