Dynamic capillary fringes - a multidisciplinary approach

毛细管缘的特征是地下水位波动，引起圈闭气体的动态形成和溶解。由于相不连续，通过该界面的流动和输运不能用经典理论来描述。在这个子项目中，我们想要(I)利用X射线照相技术在高空间(0.01 mm)和高时间(1 S)分辨率下实验探索地下水位波动期间的相饱和动力学，(Ii)研究在瞬变强迫下残留气相的形成和溶解，以及(Iii)研究非相干气体传输以及它可以用走时分布和有效连续介质性质来表示的程度。实验将在与其他SP对应的Hele-Shaw细胞中进行。对水-气界面的动力学以及气泡在孔隙尺度上的运动和大小分布的光学测量将补充连续尺度分析(分辨率0.01毫米)。利用三维X射线层析成像技术获得了气泡溶解过程的孔隙几何结构，为气泡溶解过程的孔隙尺度模拟提供了依据。此外，孔结构将通过孔尺寸分布、连通性和孔-固界面曲率来量化。这些措施然后被用作输入到一个等效的微观模型，在那里可以探索详细的多相动力学。这将为将结构性质、外力和流体性质与在CP中央实验装置中观察到的有效性质联系起来提供实验基础。

The capillary fringe is characterized by the fluctuating water table evoking the dynamic formation and dissolution of trapped gas. Due to phase discontinuities flow and transport across this interface cannot be described by classical theory. In this sub-project we want to (I) experimentally explore the dynamics of phase saturation during water table fluctuations at a high spatial (0.01 mm) and high temporal (1 s) resolution using X-ray radiography, (ii) investigate the formation and dissolution of a residual gas phase under transient forcing, and (iii) study incoherent gas transport and the extent to which it may be represented by travel time distributions and effective continuum properties. The experiments will be run in Hele- Shaw cells corresponding to the other SPs. The continuum scale analysis will be complemented by optical measurements of the dynamics of water-gas interfaces and the movement and size distribution of gas bubbles at the pore scale (resolution 0.01 mm). Using 3D X-ray tomography the structure of the pore geometry is obtained which provides the basis for pore scale modeling of the dissolution of gas bubbles (SP2). Moreover, the pore structure will be quantified in terms of pore size distribution, connectivity and pore-solid interface curvature. These measures are then used as input to an equivalent micro-model where the detailed multiphase dynamics can be explored. This will provide the experimental basis to relate structural properties, external forcing and fluid properties to effective properties observed in the central experimental facility of CP.