TY - JOUR T1 - Some Properties of Free Boundary for Solution of Porous Medium Equation with Gravity Term in One-dimension AU - Lu Guofu JO - Journal of Partial Differential Equations VL - 2 SP - 19 EP - 35 PY - 1991 DA - 1991/04 SN - 4 DO - http://doi.org/ UR - https://global-sci.org/intro/article_detail/jpde/5765.html KW - porous medium equation KW - gravity term KW - free boundary KW - C¹ regularity KW - waiting time AB - Consider the degenerate parabolic equation (porous medium equation with gravity term): u_t = (u^m)_{xx} + (u^n)_x, -∞ < x < ∞, t > 0, m > 1 u(x, 0) = u_0(x), -∞ < x < ∞ The main results consist of the estimation of t^∗_i called waiting time, the behavior of pressure V = \frac{m}{m-1}u^{m-1} near a vertical or a nonvertical part of ς_i(t) and a condition of that ς_i(t) is continuously differentiable.