EXTENDED LARGE-Q POTTS-MODEL SIMULATION OF FOAM DRAINAGE

We study the vertical liquid profile of foam drainage using the three- dimensional large-Q Potts model extended to include gravity. Forced dr ainage with constant-rate liquid input from the top of the foam produc es a constant profile. In free drainage, without liquid input from the top, homogeneously distributed liquid drains to the bottom of the foa m until capillary effects and gravity balance. For pulsed drainage, as liquid drains from the top of the foam into the dry foam, a sharp int erface between the wet and dry foam develops. The fixed profile moves downwards at a constant velocity with a flat interface. The results of our simulations are suggested in both experiments and simplified mean -field analytical results.