Computational modelling of fire propagation is becoming one of the main tools for forest fire studies. Complex physical models are coping with increasingly larger scales and meshes that no longer can accommodate trees at individual level. Therefore, it is important to know how fire propagation is influenced by tree trunks under windy conditions in order to include that information in the model and in the cells that contain trees. It is also important to know how the flame affects the trunk, especially in its leeward side where the flame may stay attached.To gather that type of information, a set of experiments was performed in a wind tunnel especially prepared to carry out fire propagation tests in forest fuel beds. A Pinus pinaster trunk was mounted vertically in the centre of the 1.70 m long measuring zone. Temperature time profiles were measured in the windward, lateral, and leeward sides of the trunk, with three thermocouples vertically aligned in each of those three sides. Rate of spread, flame angle, and flame height were obtained from video movies, as well as flame height and residence time of the attached flame in the near-wake of the trunk.Qualitative and quantitative results show that flame propagation is not particularly sensitive to the trunk's presence, except in the near-wake of the trunk. Under certain circumstances, flames attached to the leeward side of the trunk can be much taller than the flame's main body and can remain in that zone for longer periods than elsewhere.

The clarifying effect of using bis‐oxalamide compounds on linear low density polyethylene (LLDPE) has been investigated for the first time. It was demonstrated that the haze of a commercial LLDPE resin, DOWLEX™ 2045G, can be reduced up to 50% by adding 0.2 wt % of a bis‐oxalamide clarifying agent. The investigations on the crystalline morphology revealed that the density of spherulite cores increased with increasing concentration of bis‐oxalamide N5. Through an investigation of structure‐property relationships based on the tunable bis‐oxalamide structure, it was demonstrated that the combination of linear alkyl core and cyclohexyl pendant groups showed the best clarification. The interactions of clarifying molecules were simulated using dynamic molecular simulation. The simulation suggested that the rigidity of the core functionality played a role on the hydrogen bonding in the intermolecular network, which may contribute to the macroscopic clarification performance. POLYM. ENG. SCI., 58:142–149, 2018. © 2017 Society of Plastics Engineers