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| Titel |
Simulation of film and droplet flow on wide aperture fracture using Smoothed Particle Hydrodynamics |
| VerfasserIn |
J. Kordilla, A. Tartakovsky, T. Geyer |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250059559
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| Zusammenfassung |
| Fractured media provide rapid flow pathways for water percolating through the unsaturated
zone. Film flow has been widely acknowledged as a major rapid flow process with average
velocities of 3x10-7m/s (Tokunaga, 1997). Further flow regimes such as droplets, rivulets and
falling films may reach much higher velocities while coexisting with films (Ghezzehei, 2004).
In order to establish a unified description of multiphase flow at such small scales simulation
approaches have to be able to deal with the highly dynamical interfaces and reproduce the
physical behavior dominated by capillary, surface tension and gravitational forces. In
this work we show simulations of free-surface flow on inclined fracture surfaces
using a Smoothed Particle Hydrodynamics (SPH) model (Tartakovsky, 2005). The
three-dimensional Lagrangian code employs an interpolation kernel in order to
solve the Navier-Stokes equation at an arbitrary set of points (particles). Pairwise
fluid-fluid and solid-fluid interaction forces are used to simulate a wide range of wetting
conditions and Reynolds numbers encountered in laboratory experiments. Model
results are verified with empirical and semianalytical solutions. Contact angles of
droplets in a critical state, i.e. at the verge of movement, are compared with laboratory
experiments reported in literature. Transient droplet dynamics are shown to reproduce the
linear scaling proposed by Podgorski (2001). Depending on Reynolds number and
static contact angles droplets leave behind trailing films. In order to investigate
the influence of adsorbed films on droplet flow surfaces are prewetted with a thin
film and simulations repeated. The results indicate a strong dependence of droplet
flow dynamics on the existence of adsorbed films with droplet velocities being
tripled under certain conditions. Despite their relatively slow velocities, adsorbed
films are shown to be an essential part of unsaturated droplet flow dynamics as they
enhance the wetting and dewetting dynamics processes at the three-phase contact
line.
References:
T. A. Ghezzehei (2004): “Constraints for flow regimes on smooth fracture surfaces,” Water
Resour. Res., 40:1-14.
T. Podgorski, J.-M. Flesselles, and L. Limat (2001): “Corners, Cusps, and Pearls in Running
Drops”, Phys. Rev. Lett., 87(3):1-4.
A. M. Tartakovsky and P. Meakin (2005): “Modeling of surface tension and contact angles
with smoothed particle hydrodynamics”, Phys. Rev. E, 72:1-9.
T. K. Tokunaga and J. Wan (1997): “Water film flow along fracture surfaces of porous rock”.
Water Resour. Res., 33(6):1287. |
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