Primary and Secondary Infiltration of Wetting Liquid Sessile Droplet into Porous Medium |
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Authors: | B Markicevic H K Navaz |
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Institution: | (1) Department of Mechanical Engineering, Kettering University, 1700 West Third Avenue, Flint, MI 48504, USA |
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Abstract: | The infiltration of a wetting droplet into the porous medium is a two-step process referred to as primary and secondary infiltration.
In the primary infiltration there is a free liquid present at the porous medium surface, and when no fluid is left on the
surface, the secondary infiltration is initiated. In both situations the driving force is the capillary pressure that is influenced
by the local medium heterogeneities. A capillary network model based on the micro-force balance is developed with the same
formulation applied to both infiltrations. The only difference between the two is that the net liquid flow into the porous
medium in the secondary infiltration is equal to zero. The primary infiltration starts as a single-phase (fully saturated)
flow and may proceed as a multiphase flow. The multiphase flow emerges as the interface (flow front) becomes irregular in
shape. The immobile clusters of the originally present phase can be locally formed due to entrapment. Throughout the infiltration,
it was found that portions of the liquid phase can be detached from the main body of the liquid phase forming some isolated
liquid ganglia that increase in number and decrease in size. The termination of the secondary infiltration occurs once the
ganglia become immobile due to their reduction in size. From the transient solution, the changes in the liquid saturation
and capillary pressure during the droplet infiltration are determined. The solution developed in this study is used to investigate
the droplet infiltration dynamics. However, the solution can be used to study the flow in fuel cell, nano-arrays, composites,
and printing. |
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Keywords: | |
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