Flow split characterization of two immiscible phases with different wettability scenarios: A numerical investigation using a coupled Cahn–Hilliard and Navier–Stokes system

Bao, Kai; Salama, Amgad; Sun, Shuyu

doi:10.1016/j.ijmultiphaseflow.2017.12.016

Cited by 16 publications

(8 citation statements)

References 29 publications

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“…The interface that separates the two phases represents a surface of discontinuity in the realm of sharp interface models, 44–49 or is considered part of the domain with particular thickness in the realm of diffuse interface models. 50,51 However, the difficulty in adapting a framework for modeling the motion of two-phase systems as one fluid is very much related to identifying the proper way to represent the interfacial tension forces (which are essentially surface forces) as a volumetric force. This has been tackled by Hirt and Nichols.…”

Section: Cfd Investigationmentioning

confidence: 99%

On the estimation of the size of a droplet emerging from a pore opening into a crossflow field

Salama

2022

Soft Matter

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Section: Cfd Investigationmentioning

confidence: 99%

On the estimation of the size of a droplet emerging from a pore opening into a crossflow field

Salama

2022

Soft Matter

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“…Models related to the flow of multiphase systems are very much dependent on the type of flow regime. They can generally be classified into continuum-type approaches, lumped parameter approaches, or interface-tracking approaches (e.g., volume of fluid (VOF) method [ 43 ], level-set method [ 44 ], diffuse interface model [ 45 , 46 ], and lattice Boltzmann methods [ 47 ]). In this research, since we were interested in the fate of oil droplets at the surface of the membrane under oleophobicity deterioration, interface tracking methods were used.…”

Section: Cfd Investigationmentioning

confidence: 99%

The Effect of the Oleophobicity Deterioration of a Membrane Surface on Its Rejection Capacity: A Computational Fluid Dynamics Study

et al. 2021

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In this work, the effects of the deteriorating affinity-related properties of membranes due to leaching and erosion on their rejection capacity were studied via computational fluid dynamics (CFD). The function of affinity-enhancing agents is to modify the wettability state of the surface of a membrane for dispersed droplets. The wettability conditions can be identified by the contact angle a droplet makes with the surface of the membrane upon pinning. For the filtration of fluid emulsions, it is generally required that the surface of the membrane is nonwetting for the dispersed droplets such that the interfaces that are formed at the pore openings provide the membrane with a criterion for the rejection of dispersals. Since materials that make up the membrane do not necessarily possess the required affinity, it is customary to change it by adding affinity-enhancing agents to the base material forming the membrane. The bonding and stability of these materials can be compromised during the lifespan of a membrane due to leaching and erosion (in crossflow filtration), leading to a deterioration of the rejection capacity of the membrane. In order to investigate how a decrease in the contact angle can lead to the permeation of droplets that would otherwise get rejected, a CFD study was conducted. In the CFD study, a droplet was released in a crossflow field that involved a pore opening and the contact angle was considered to decrease with time as a consequence of the leaching of affinity-enhancing agents. The CFD analysis revealed that the decrease in the contact angle resulted in the droplet spreading over the surface more. Furthermore, the interface that was formed at the entrance of the pore opening flattened as the contact angle decreased, leading the interface to advance more inside the pore. The droplet continued to pass over the pore opening until the contact angle reached a certain value, at which point, the droplet became pinned at the pore opening.

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“…The problem will even be more complicated should the object be another fluid immiscible with the surrounding fluid. The governing equations that are applicable to all phases represent conservation laws of mass and momentum [ 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. As mentioned, these equations can apply to all fluid regions augmented with equations at the interface between phases.…”

Section: Governing Equationsmentioning

confidence: 99%

“…In the context of this work, we adopt the assumption of no jump in the shear stress on the interface. Our motive in this stems from the sharp interface limit in which the interface represents a surface of discontinuity deprived from any physical properties [ 26 , 27 ]. Such an assumption, together with the sharp interface limit argument, implies the following two points—namely, (1) no jump in the velocity at the interface, (2) no jump in the shear stress along the interface as long as there is no gradient in the interfacial tension.…”

Section: Introductionmentioning

confidence: 99%

A Unified, One Fluid Model for the Drag of Fluid and Solid Dispersals by Permeate Flux towards a Membrane Surface

2021

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The drag of dispersals towards a membrane surface is a consequence of the filtration process. It also represents the first step towards the development of the problem of fouling. In order to combat membrane fouling, it is important to understand such drag mechanisms and provide a modeling framework. In this work, a new modeling and numerical approach is introduced that is based on a one-domain model in which both the dispersals and the surrounding fluid are dealt with as a fluid with heterogeneous property fields. Furthermore, because of the fact that the geometry of the object assumes axial symmetry and the configuration remains fixed, the location of the interface may be calculated using geometrical relationships. This alleviates the need to define an indicator function and solve a hyperbolic equation to update the configuration. Furthermore, this approach simplifies the calculations and significantly reduces the computational burden required otherwise if one incorporates a hyperbolic equation to track the interface. To simplify the calculations, we consider the motion of an extended cylindrical object. This allows a reduction in the dimensions of the problem to two, thereby reducing the computational burden without a loss of generality. Furthermore, for this particular case there exists an approximate analytical solution that accounts for the effects of the confining boundaries that usually exist in real systems. We use such a setup to provide the benchmarking of the different averaging techniques for the calculations of properties at the cell faces and center, particularly in the cells involving the interface.

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Flow split characterization of two immiscible phases with different wettability scenarios: A numerical investigation using a coupled Cahn–Hilliard and Navier–Stokes system

Cited by 16 publications

References 29 publications

On the estimation of the size of a droplet emerging from a pore opening into a crossflow field

On the estimation of the size of a droplet emerging from a pore opening into a crossflow field

The Effect of the Oleophobicity Deterioration of a Membrane Surface on Its Rejection Capacity: A Computational Fluid Dynamics Study

A Unified, One Fluid Model for the Drag of Fluid and Solid Dispersals by Permeate Flux towards a Membrane Surface

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