Features of turbulence during wildland fires in forested and grassland environments

Fire-induced turbulence and the feedback into fire, following ambient changes, differ for forested (sub-canopy) grassland environments. Here, we synthesize observations from multiple experimental surface fires: two sub-canopy backing fires, one heading a fire. We identify compare most essential coherent structures processes of each case turbulent momentum fluxes kinetic energy (TKE) budget terms. In burns, eddies are strongest near canopy top: high streamwise flux accompanies low cross-stream vice versa. both strengthen simultaneously until certain height, informing vertical length scale fire-influence. Moreover, forward sweep assists in fire spread by pushing hot gases towards unburnt fuel. shear production buoyancy more substantial top intense while their magnitudes decrease with decreasing intensity. At mid-canopy-height scales, dominates production, becoming key mechanism transport TKE. is insignificant beyond height relative to flame length, increases further away surface. Turbulent terms also active For there loss TKE due its expulsion boundary layer aloft via term, compensated reversal process: influx term. term mimics this behavior height. The insights significance respective environment can help simplify complex system equations governing physics.