![]() ![]() Potential implications of the model and its solutions are also discussed briefly in the context of the outspread of COVID-19, employing physical parameters for exhaled droplets, paper and cloth. ![]() ![]() The model leads to evolution pathways for both the droplet and the fluid film within the porous layer, without introducing arbitrary fitting parameters. Two limiting cases are considered based on different assumptions on the motion of the contact line during the coupled process of drop drainage and patch growth: (i) the apparent contact angle remains unchanged, so the radius of a sessile droplet decreases with time and (ii) the location of the contact line remains pinned, so the contact angle decreases as time progresses. We present a theoretical model to describe how a wet patch develops gradually through imbibition, once a sessile droplet attaches at a permeable surface and drains gradually into a thin porous layer. on a piece of paper or cloth, is related to the transmission of virus particles through exhaled droplets and aerosols. Growth of a fluid-infused patch on a thin porous layer, e.g. An analysis of currently available fracture-stiffness data shows that the lack of knowledge of the stress dependence of stiffness severely hampers firm conclusions on scale dependence and the bias between methods. The parameters derived from the modelling compare well with independent constraints. The model’s application to the field data yield estimates of properties of the fractures (length, aperture, and stiffness) and of the surrounding rock mass (product of permeability and specific storage capacity). To examine the model’s characteristics, we investigated pressure transients predicted for specific cases, such as negligible fracture leakage, and subsequently numerically determined the sensitivity of the model predictions to the involved model parameters. We address the hydraulic system by considering three different “storage containers”, described by non-dimensionless storage parameters: the wellbore with a fixed storage capacity, the fracture with storage capacities related to fluid compressibility and fracture stiffness, and the surrounding rock constituting a container with unlimited storage capacity. For the evaluation of the pressure recovery, we developed a generic model that accounts for the inherent convolution of mechanical closing of the fracture, fluid flow in the fracture, fluid exchange between fracture and the surrounding rock, here addressed as fracture leakage, and effects associated with finite borehole storage. We constrained normal stiffness (and its stress dependence) of two fractures intersecting a borehole in the research mine “Reiche Zeche” in Freiberg, Saxony, Germany, from pressure-recovery behaviour observed when the pressure in a double-packer interval enclosing them was briefly released during shut-in sequences. ![]() Their visibility for elastic waves hinges on their stiffness, a measure of the relation between changes in fracture aperture and applied stress, that itself significantly increases with increasing stress according to laboratory data. Fractures are ubiquitous in Earth’s upper crust and strongly affect its physical properties. ![]()
0 Comments
Leave a Reply. |