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The Basic Concept for Microfluidics-Based Devices
Published in Raju Khan, Chetna Dhand, S. K. Sanghi, Shabi Thankaraj Salammal, A. B. P. Mishra, Advanced Microfluidics-Based Point-of-Care Diagnostics, 2022
A capillary number is the ratio of viscous forces to the surface tension acting on the interface between the two phases. Ca=ViscousForceCapillaryForce=μuσ
Introduction to the Continuum Fluid
Published in Tasos C. Papanastasiou, Georgios C. Georgiou, Andreas N. Alexandrou, ViscousFluid Flow, 2021
Tasos C. Papanastasiou, Georgios C. Georgiou, Andreas N. Alexandrou
Flows of highly viscous liquids are characterized by a vanishingly small Reynolds number and are called Stokes or creeping flows. Most flows of polymers are creeping flows [6]. The Reynolds number also serves to distinguish between laminar and turbulent flow. Laminar flows are characterized by the parallel sliding motion of adjacent fluid layers without intermixing, and persist for Reynolds numbers below a critical value that depends on the flow. For example, for flow in a pipe, this critical value is 2,100. Beyond that value, eddies start to develop within the fluid layers that cause intermixing and chaotic, oscillatory fluid motion, which characterizes turbulent flow. Laminar flows at Reynolds numbers sufficiently high that viscous effects are negligible are called potential or Euler flows. The Stokes number is zero in strictly horizontal flows and high in vertical flows of heavy liquids. The capillary number appears in flows with free surfaces and interfaces [7]. The surface tension, and thus the capillary number, can be altered by the addition of surfactants to the flowing liquids.
Liquid Contaminants in the Pore Spaces Between Soil Particles in the Saturated Zone
Published in Warren J. Lyman, Patrick J. Reidy, Benjamin Levy, Chi-Yuan Fan, Mobility and Degradation of Organic Contaminants in Subsurface Environments, 2020
Warren J. Lyman, Patrick J. Reidy, Benjamin Levy, Chi-Yuan Fan
The dimensionless ratio of capillary forces to viscous forces is known as the capillary number (Nc): () Nc=k⋅ρw⋅g⋅J∂where k = intrinsic permeability of porous medium (cm2)ρw = the density of water (g/cm3)∂ = interfacial tension (dyne/cm)g = gravitational acceleration (cm/sec2)J = hydraulic gradient (cm/cm)
Investigation on the effects of cationic surface active ionic liquid/anionic surfactant mixtures on the interfacial tension of water/crude oil system and their application in enhancing crude oil recovery
Published in Journal of Dispersion Science and Technology, 2023
Yingbiao Xu, Tingyi Wang, Lingyu Zhang, Yongan Tang, Wenjian Huang, Han Jia
Surfactants can largely reduce water/crude oil IFT to increase capillary number by two or three orders of magnitude, leading to the remarkable decrease of residual oil saturation.[7–9] While it was demonstrated that a large number of conventional surfactants were not applicable for unconventional reservoirs with high salinity and high temperature.[10,11] Compared with traditional surfactants, ionic liquids (ILs) are non-nontoxic, environmentally friendly, non-corrosive,[12] and featured by low melting points (<100 °C), negligible vapor pressure, favorable thermal stability, and high ionic conductivity.[13,14] As the typical organic salts, ILs contain organic cations (i.e., imidazolium, pyrrolidine, and pyridinium cations) and inorganic anions (i.e., [BF4]−, [PF6]−, Cl−, and Br− anions), both of which can be altered to modify the IL’s properties.[15] The ILs with long alkyl chains were regarded as surface active ionic liquids (SAILs), which were widely employed in multiple fields, including the fabrications of nanomaterials,[16] cellulose dissolution,[17] the separation of substances,[18] and chemical EOR.
Heat Transfer in Laminar Graetz and Taylor Flows Incorporating Nanoparticles
Published in Heat Transfer Engineering, 2022
Khalifa Alrbee, Yuri Muzychka, Xili Duan
The surface tension of base fluid/water was predicted based on average bulk temperature using one of the best correlations that was given by Vargaftik et al. [59] and Jabez et al. [60]. The determined values of surface tension revealed a slight variation over temperature range of the conducted experiments of 71.05 71.12 . Typically, capillary number is important to be reported in Taylor flow experiments. For the water-gas Taylor flow experiments, was calculated to be within the range of 3.38 13.72 Adding nanoparticles to conventional fluids cause surface tension to increase [53, 59, 60]. Table 5 contains predicted values of surface tension using Sysyzkowskim model Eq. (17) [53]. In the present study, increase of nanoparticle concentration 2 to 4 wt% led to an increase of surface tension from 75.9 to 76.26 mN/m. A slight variation was observed on surface tension of nanofluids over the considered range of temperature in the present study.
Effects of relative permeability change resulting from interfacial tension reduction on vertical sweep efficiency during the CO2-LPG hybrid EOR process
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2018
Jinhyung Cho, Tae Hong Kim, Namjoon Chang, Kun Sang Lee
Capillary number, which is the ratio of viscous to capillary forces, increases with decreasing IFT between gas and oil, and higher capillary number improves gas and oil relative permeability (Araujo et al. 2001; Jamaloei 2015; McDougall, Salino, and Sorbie 1997). The vapor/liquid relative permeability curve presented by Bardon and Longeron (1980) was used in this work. The relative permeability curves for gas and oil became linear functions of the respective saturations when they became indistinguishable, meaning that IFT approached zero. The expressions for and , which denote the modified and caused by the IFT change, are written as follows: