Experimental results of one-sided upward flame spread over wavy cellulosic paper samples are presented. The sinusoidal shaped samples with different wave length and amplitude are aligned perpendicular to the gravitational direction so the upward buoyant flow sees peak and valley along its flow path. Depending on the wave amplitude and wave length, the flame can spread from sample peak to peak initially but may later sustain slow burning from isolated flamelets inside the sample valleys or become quenched. The degree of fuel burning completeness, pyrolysis front spread rate and extinction limits (both local and overall) depend on the wavy parameters in a complex way as well as the ambient relative humidity. Flame spread over wavy samples thus has unique features not found in continuous flat samples or in discrete samples. Video record of the experiments supplied in the paper presents both the front and the side views of these interesting transient flame development.
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