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Title: Smoothed particle hydrodynamics study of the roughness effect on contact angle and droplet flow

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Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21)
OSTI Identifier:
Grant/Contract Number:
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review E
Additional Journal Information:
Journal Volume: 96; Journal Issue: 3; Related Information: CHORUS Timestamp: 2017-09-28 15:44:36; Journal ID: ISSN 2470-0045
American Physical Society
Country of Publication:
United States

Citation Formats

Shigorina, Elena, Kordilla, Jannes, and Tartakovsky, Alexandre M. Smoothed particle hydrodynamics study of the roughness effect on contact angle and droplet flow. United States: N. p., 2017. Web. doi:10.1103/PhysRevE.96.033115.
Shigorina, Elena, Kordilla, Jannes, & Tartakovsky, Alexandre M. Smoothed particle hydrodynamics study of the roughness effect on contact angle and droplet flow. United States. doi:10.1103/PhysRevE.96.033115.
Shigorina, Elena, Kordilla, Jannes, and Tartakovsky, Alexandre M. 2017. "Smoothed particle hydrodynamics study of the roughness effect on contact angle and droplet flow". United States. doi:10.1103/PhysRevE.96.033115.
title = {Smoothed particle hydrodynamics study of the roughness effect on contact angle and droplet flow},
author = {Shigorina, Elena and Kordilla, Jannes and Tartakovsky, Alexandre M.},
abstractNote = {},
doi = {10.1103/PhysRevE.96.033115},
journal = {Physical Review E},
number = 3,
volume = 96,
place = {United States},
year = 2017,
month = 9

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on September 28, 2018
Publisher's Accepted Manuscript

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  • We employ a pairwise force Smoothed Particle Hydrodynamics (PF-SPH) model to simulate sessile and transient droplets on rough hydrophobic and hydrophilic surfaces. PF-SPH allows for modeling of free surface flow without discretizing the air phase, which is achieved by imposing the surface tension and dynamic contact angles with pairwise interaction forces. We use the PF-SPH model to study the effect of surface roughness and microscopic contact angle on the effective contact angle and droplet dynamics. In the first part of this work, we investigate static contact angles of sessile droplets on rough surfaces in a shape of a sinusoidal functionmore » and made of rectangular bars placed on top of a flat surface. We find that the effective static contact angles of Cassie and Wenzel droplets on a rough surface are greater than the corresponding microscale static contact angles. As a result, microscale hydrophobic rough surfaces also show effective hydrophobic behavior. On the other hand, microscale hydrophilic surfaces may be macroscopically hydrophilic or hydrophobic, depending on the type of roughness. Next, we study the impact of the roughness orientation (i.e., an anisotropic roughness) and surface inclination on droplet flow velocities. Simulations show that droplet flow velocities are lower if the surface roughness is oriented perpendicular to the flow direction. If the predominant elements of surface roughness are in alignment with the flow direction, the flow velocities increase compared to smooth surfaces, which can be attributed to the decrease in fluid-solid contact area similar to the classical lotus effect. We demonstrate that linear scaling relationships between Bond and capillary number for droplet flow on flat surfaces also hold for flow on rough surfaces.« less
  • Flow on fracture surfaces has been identified by many authors as an important flow process in unsaturated fractured rock formations. Given the complexity of flow dynamics on such small scales, robust numerical methods have to be employed in order to capture the highly dynamic interfaces and flow intermittency. In this work we present microscale free-surface flow simulations using a three-dimensional multiphase Smoothed Particle Hydrodynamics (SPH) code. Pairwise solid-fluid and fluid-fluid interaction forces are used to control the wetting behavior and cover a wide range of static and transient contact angles as well as Reynolds numbers encountered in droplet flow onmore » rock surfaces. We validate our model via comparison with existing empirical and semi-analyical solutions for droplet flow. We use the model to investigate the occurence of adsorbed trailing films of droplets under various flow conditions and its importance for the flow dynamics when films and droplets coexist. We show that flow velocities are higher on prewetted surfaces covered by a thin film which is qualitatively attributed to the enhanced dynamic wetting and dewetting at the trailing and advancing contact line.« less
  • We present a novel formulation of the Pairwise Force Smoothed Particle Hydrodynamics Model (PF-SPH) and use it to simulate two- and three-phase flows in bounded domains. In the PF-SPH model, the Navier-Stokes equations are discretized with the Smoothed Particle Hydrodynamics (SPH) method and the Young-Laplace boundary condition at the fluid-fluid interface and the Young boundary condition at the fluid-fluid-solid interface are replaced with pairwise forces added into the Navier-Stokes equations. We derive a relationship between the parameters in the pairwise forces and the surface tension and static contact angle. Next, we demonstrate the accuracy of the model under static andmore » dynamic conditions. Finally, to demonstrate the capabilities and robustness of the model we use it to simulate flow of three fluids in a porous material.« less
  • Cited by 14
  • A two-dimensional numerical model based on smoothed particle hydrodynamics (SPH) was used to simulate unsaturated (multiphase) flow through fracture junctions. A combination of standard SPH equations with pair-wise fluid-fluid and fluid-solid particle-particle interactions allowed surface tension and three-phase contact dynamics to be simulated. The validity of the model was verified by calculating the surface tension in four different ways: 1. from small amplitude oscillations of fluid drops; 2. from the dependence of the capillary pressure on drop radius; 3. from capillary rise simulations; and 4. from the behavior of a fluid drop confined between parallel walls under the influence ofmore » gravity. All four simulations led to consistent values for the surface tension.. The dependency of receding and advancing contact angles on droplet velocity was studied. Incorporation of surface tension and fluid-solid interactions allowed unsaturated flow through fracture junctions to be realistically simulated, and the simulation results compare well with the laboratory experiments of Dragila, and Weisbrod.« less