School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; State Key Lab of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
Hubei Subsurface Multi-scale Imaging Key Laboratory, Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China.
J Colloid Interface Sci. 2018 Jul 1;521:226-231. doi: 10.1016/j.jcis.2018.03.050. Epub 2018 Mar 15.
The effect of gravity was generally neglected in the classical imbibition law for one dimensional geometries. Following researches complemented the classical "Lucas-Washburn law" with consideration of gravity, but no examination of geometries under influence of gravity has been done, while geometry was shown to yield different scaling law for the imbibition process. Hence, it is possible to discover new time exponents for imbibition length in two dimensional and three dimensional imbibition process under gravity.
Through theoretical analysis and numerical simulations, the size of wetted region under three gravitational scenarios (zero gravity, acceleration and deceleration) in three geometries (one dimensional, two dimensional radial and three dimensional radial) are determined quantitatively.
New time exponents other than classic 1/2 are identified under different directions of gravity in two dimensional radial and three dimensional radial imbibition, and symmetry of time exponents due to different directions of gravity is discovered. A new time exponent of 1 for the acceleration case in one dimensional imbibition is found. The flow field in the wetted region is also determined from simulations. Discoveries in this paper show that new physical laws for imbibition length exist at the intersection of gravity and geometry.
在一维几何形状的经典吸吮定律中，通常忽略重力的影响。后续的研究通过考虑重力对经典的“Lucas-Washburn 定律”进行了补充，但没有对受重力影响的几何形状进行检查，而几何形状对吸吮过程产生了不同的比例定律。因此，有可能在重力作用下的二维和三维吸吮过程中发现新的吸吮长度时间指数。
通过理论分析和数值模拟，定量确定了在三种重力情况下（零重力、加速和减速）三种几何形状（一维、二维径向和三维径向）下润湿区域的大小。
在二维径向和三维径向吸吮中，在不同重力方向下确定了除经典 1/2 以外的新时间指数，并且发现了由于不同重力方向导致的时间指数的对称性。在一维吸吮中，发现了加速情况下的新时间指数 1。还从模拟中确定了润湿区域中的流场。本文的发现表明，在重力和几何形状的交点处存在新的吸吮长度物理定律。
