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Abstract. In Part I of this paper, we have introduced the
Mason-Morrow shape factor and the corner half-angles to capture the
part of geometry of angular capillaries essential in pore network
calculations of single and two-phase flow in drainage and imbibition.
We then used this shape factor to obtain simple expressions for the
hydraulic conductance in single-phase flow through triangular,
rectangular and oval capillaries. In Part II, we study two-phase fluid
flow along angular capillaries. The nonwetting fluid occupies the
central part of the capillary, whereas the wetting liquid fills the
corners. First, we verify the numerical solution obtained by
Ransohoff-Radke for concave corner menisci by using a high-resolution
finite element method with zero and infinite surface shear viscosity.
We present new numerical results for corner flow domains bounded by
convex menisci, i.e., for pinned contact lines and forced imbibition.
We also present numerical solutions for two-phase flow with momentum
transfer across the interface. We introduce a dimensionless hydraulic
conductance of wetting fluid in the corners and correlate it with the
corner filament shape factor, corner half angle and contact angle. By
appropriate scaling, we obtain an accurate universal curve for flow
conductance in the corners of an arbitrary angular capillary and for
arbitrary contact angles. We give error estimates of the
Ransohoff-Radke flow resistance factors, the Zhou et al.
analytical expressions for the resistance factors, and of our
universal curves for the hydraulic conductance with no-slip and
perfect slip boundary conditions at the interface. Our expressions for
the hydraulic conductance in corner flow of wetting liquid are not
only valid for both concave and convex fluid interfaces, but are more
accurate than any other published correlation.
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