Numerical study of the effects of contact angle and viscosity ratio on the dynamics of snap-off through porous media

Michele Starnoni, Dubravka Pokrajac

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Snap-off is a pore-scale mechanism occurring in porous media in which a bubble of nonwetting phase displacing a wetting phase, and vice-versa, can break-up into ganglia when passing through a constriction. This mechanism is very important in foam generation processes, enhanced oil recovery techniques and capillary trapping of CO2 during its geological storage. In the present study, the effects of contact angle and viscosity ratio on the dynamics of snap-off are examined by simulating drainage in a single pore-throat constriction of variable cross-section, and for different pore-throat geometries. To model the flow, we developed a CFD code based on the Finite Volume method. The Volume-of-fluid
method is used to track the interfaces. Results show that the threshold contact angle for snap-off, i.e. snap-off occurs only for contact angles smaller than the threshold, increases from a value of 28◦ for a circular cross-section to 30-34◦
for a square cross-section and up to 40◦ for a triangular one. For a throat of square cross-section, increasing the viscosity of the injected phase results in a drop in the threshold contact angle from a value of 30◦ when the viscosity ratio µ is equal to 1 to 26◦ when µ = 20 and down to 24◦ when µ = 20.
Original languageEnglish
Pages (from-to)70-85
Number of pages16
JournalAdvances in Water Resources
Early online date16 Nov 2017
Publication statusPublished - 1 Jan 2018



  • numerical simulations
  • snap-off
  • contact angle
  • viscosity ratio

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