Phases of damage propagation during a windstorm

Here is a slide from my PhD defence, showing the different evolution phases of damage propagation during a windstorm ( Same simulation as the animations published here the 19/11/2014 )

And here is a serie of results (from chapter 4 of my PhD dissertation) showing the two main phases ( 1 - damage start/ first minor gust (dashed line) and 2 - damage propagation acceleration/ more important gust (continuous line). Phases 1 and 2 can be the same, phase 2 can never occured.

These different cases are related to a study concerning the effect of foliar area reduction on damage propagation.

Modelling wind damage propagation in a homogeneous forest

This is chapter 3 of my PhD dissertation (also available on ResearchGate):

https://drive.google.com/file/d/0ByVlxqWw8eVkRTgyRXFFNVVHYzQ/view?usp=sharing

Abstract: In order to investigate wind-tree interaction and tree damage propagation in windstorm conditions, a tree swaying model accounting for large tree deflections and considering the possibility of tree breakage is coupled with a large-eddy simulation airflow model. The model is applied on a homogeneous Maritime pine forest under windstorm conditions. It is first shown that the well-known characteristics of canopy flow remain identical in windstorm conditions and that tree motion has a negligible impact on the wind dynamics. Then, tree damage propagation during windstorms is analysed in relation to windstorm intensity. Under similar conditions the level of damages can differ significantly between two identical stands, depending on the occurrence of critical gusts. Once the first damages are initiated, the velocity of damage propagation is similar for windstorms of similar intensity and increases exponentially with windstorm intensity. This is the first time that tree damages are explicitly simulated using an airflow model applied in windstorm conditions.


Keywords: Fluid-structure interaction - Tree motion - Turbulent flow - Large eddy simulation - Wind damage - Windstorm.