As two or more freely burning fires converge, their behavior can change, significantly. Flamelength, flameangle, heat release rate, and propagation rate for spreading fires have all been observed to increase during flame merging. These fire interactions can prove challenging for fire fighters who are often required to adjust tactics to maintain control of the fire. Forest Service scientists studied the fluid mechanics of two adjacent line fires theoretically and experimentally. They validated a fire behavior model by measuring the velocity field surrounding stationary alcohol pool fires, and the measured velocities and flame angles compared reasonably with the predicted values.