GROWTH AND DECAY OF STREAKS AND WAVES ON THE FORMING TABLE

Surface waves and streaks on the forming table can lead to nonuniform basis weight and moisture profile across the sheet. In this study, we analyze the effects of viscosity and drainage on the decay of surface waves and streaks on the forming table. Large scale variations in phys ical properties that scale with the width of the paper machine are rel atively well understood. In contrast, the cause of the small scale non uniformities in the physical properties are not well understood. The l ength scales we refer to as ''small scale'' in this study are relative to the machine width and range from 0.2 m to 0.5 m. Specifically, ult rasonic stiffness measurements of linerboard samples from commercial p aper machines show small scale fluctuations in addition to the overall variations in the cross-machine direction. Analysis of the paper mach ine shows no physical features with the same length scale that could c ause these nonuniformities except the wet streaks at the dry line on t he forming table. We show the mechanism by which the streaks on the fo rming table evolve to form the characteristic nonuniformities in basis weight, moisture, and stiffness properties.