Silicone Oil Research Articles

Spatiotemporal Filter Velocimetry With Arbitrary-Shaped Measurement Region For Accurate Measurement In The Vicinity Of A Boundary

Viscous stress at a boundary or an interface is a source of drag acting on a body or a fluid particle and therefore its measurement is of great importance for understanding the motion of the body or the fluid particle. In this study, spatiotemporal filter velocimetry (SFV: Hosokawa & Tomiyama, 2012) is extended to arbitrary quadrilateral measurement areas fitted to an interface shape for accurate measurement of flow about a deformed drop, and it is applied to flows about single drops of glycerol-water solution falling in stagnant silicon oil under clean and contaminated conditions. Figure 1 shows the trajectories of tracer particles and the measured velocity distributions. No separation is observed for the spherical and ellipsoidal drops. On the other hand, the stagnant region is observed in the dimple region of the tail of the cap drop. These results clearly indicate that the flow about the deformed drop is successfully measured by SFV with arbitrary quadrilateral measurement areas. Figure 2 shows the trajectories of tracer particles and the measured velocity distributions of single ellipsoidal drops in clean and contaminated systems. Triton X-100 was used as the surfactant and its concentration C in the drop ranges from 0.0 to 0.1 mol/m3 . The drop tail becomes flat and then slightly dimpled shape, and the internal circulation becomes weak as C increases. The internal circulation remains even at the high surfactant concentration condition under which the internal circulation in single spherical drop is fully damped (Hosokawa et al., 2017). We also evaluate interfacial velocity, interfacial shear stresses, the Marangoni stress and surfactant concentration at the interface from measured velocity distributions in the vicinity of the interface. As a result, we confirmed that SFV enables us to measure velocity distribution about a single deformed drop and enables us to evaluate interfacial velocity, interfacial shear stresses, the Marangoni stress and surfactant concentration at the interface.

The Tribological and Adsorption Performance of Chlorophenyl Silicone Oil Using Different Ceramic Materials under High Temperature

With the development of technical requirements, the current challenges faced by bearing materials mainly revolve around high-temperature conditions and the trend towards material lightweighting. Full ceramic bearings are the new candidate due to their excellent properties. This article details the tribological and adsorption performance of chlorophenyl silicone oil (CPSO) as a high-temperature lubricant in ceramic tribological systems (ZrO2, Al2O3, and Si3N4). Among the three ceramic tribological systems, the lubrication performance can be ordered as Si3N4 > Al2O3 > ZrO2, as the wear rates of the ZrO2 and Al2O3 tribo-systems are almost 1135.67 and 283.33 times larger than that of the Si3N4 tribo-system, respectively. The observed results can be explained by the superior adsorption performance of CPSO on a Si3N4 ceramic surface, which was calculated by molecular dynamic simulation. The molecular dynamic simulation results show the adsorption energy of CPSO/Si3N4 is almost 54.09 and 61.18 times higher compared to that on ZrO2 and Al2O3 ceramics. These findings provide experimental and theoretical insights for understanding the lubrication performance of CPSO in a full ceramic tribo-system.

Viscoelastic, Optical, and Surgical Properties of Vitreous Body Replacement Hydrogels After Aging Compared to Porcine Vitreous Bodies And Silicone Oils.

First- (monomers), second- (pre-gelated), and third- (in situ gelating after injection) generation hydrogels were previously introduced to replace the vitreous body after vitrectomy surgery. In this study, we evaluated the surgical, optical, and viscoelastic properties of vitreous body replacement hydrogels before and after an accelerated aging protocol previously applied to intraocular implants. Measurements of injection force, removal speed using a clinically established vitrectomy setup, as well as evaluation of forward light scattering and viscoelastic properties before and after an accelerated aging protocol were conducted. Results were compared to porcine and human vitreous bodies, as well as currently clinically applied lighter- and heavier-than-water silicone oils. Removal speed of all tested hydrogels is substantially lower than the removal speed of porcine vitreous body (0.2 g/min vs. 2.7 g/min for the best performing hydrogel and porcine vitreous body, respectively). Forward light scattering in second-generation vitreous body replacement hydrogels was higher after the aging process than the straylight of the average 70-year-old vitreous body (9.4 vs. 5.5 deg2/sr, respectively). The viscoelastic properties of all hydrogels did not change in a clinically meaningful manner; however, trends toward greater stiffness and greater elasticity after aging were apparent. This study demonstrates surgical weaknesses of the hydrogels that need to be addressed before clinical use, especially low removal speed. Pre-linked hydrogels (second-generation) showed inferior performance regarding surgical properties compared to in situ gelating hydrogels (third-generation). This study highlights possible pitfalls regarding surgical and optical properties when applying vitreous replacement hydrogels clinically.

Hydroxyproline Concentration and Associated Factors of Preserved Small Incision Lenticule Extraction-Derived Corneal Stromal Lenticules.

To evaluate changes of hydroxyproline concentration and its influencing factors of small incision lenticule extraction (SMILE)-derived corneal stromal lenticules with different preservation methods. A total of 390 corneal stromal lenticules of 195 patients were derived from SMILE surgeries. Thirty of the lenticules were classified as the fresh (control) group, and the rest were randomly and evenly divided and stored in anhydrous glycerol, silicone oil, Optisol, and cryopreservation for 1 day, 1 week, or 1 month. A hydroxyproline assay kit (ab222941, Abcam) was used to measure the hydroxyproline concentration in each preservation method. Concentrations of MMP-2, TIMP-2, TNFα, TGFβ2, and reactive oxygen species were also evaluated. In the anhydrous glycerol group, the concentration of hydroxyproline decreased within 1 week (fresh: 1 dΔ = 0.229, P < 0.001*; 1 d - 1 wΔ = 0.055, P < 0.001*) while that in the silicone oil group remained stable in 1 week (1 d - 1 wΔ = -0.005, P = 0.929) and decreased significantly in 1 m (1 m - 1 wΔ = -0.041, P = 0.003*). The sequence of hydroxyproline concentration in the Optisol group was 1 m > 1 day > 1 week. Hydroxyproline concentration in the cryopreservation group decreased within 1 m. Hydroxyproline concentration was highest in the Optisol group and lowest in the anhydrous glycerol group under the same preservation time. Hydroxyproline concentration was negatively correlated with MMP-2 (r = -0.16, P = 0.421) and TIMP-2 (r = -0.56, P = 0.002*) while MMP-2 and TNFα (r = 0.17, P = 0.242), TIMP-2 and TGFβ2 (r = 0.21, P = 0.207), and TNFα and reactive oxygen species (r = 0.52, P = 0.007*) were positively correlated. More collagen was retained in SMILE lenticules preserved in Optisol under the same preservation time. The mechanism of the changes of collagen in preserved SMILE-derived lenticules and oxidative stress requires additional investigation.

The effect of silicone oil on the anatomical and functional parameters of the retina during surgery of regmatogenic retinal detachment

Vitrectomy followed by endotamponade of the vitreal cavity with silicone oil (SO) is one of the main techniques of treating severe forms of regmatogenic retinal detachment (RRD). Endotamponade with SO, having numerous advantages and a huge potential, carries the risk of a number of complications arising at various times of application. The literature review analyzes the published data on the effect of tamponade SO on the retina and the function of central vision in RRD surgery: visual acuity, indicators of light and color sensitivity, data of electrophysiological test results. Possible causes of deteriorated central vision functions directly or indirectly related to tamponade with SO are discussed: changes in the thickness and structure of the retina or its individual layers as shown by optical coherence tomography (OCT) data, microcirculation disorders according to OCT angiography, fluorescein angiography, Doppler laser scanning, as well as pathohistological findings related to SO migration into the fundus of eye tissues.

Investigating the Effects of Lubricant Infusion Methods on Polymer SLIPS.

Slippery lubricant infused porous surfaces (SLIPSs) are promising bioinspired surfaces with self-healing and droplet wetting properties, among many others, that are desirable due to their range of applications. Recently, there have been many developments in the SLIPS field regarding the creation of textured surfaces and lubricant selection. However, there is a lack of knowledge regarding the method of lubricant infusion. In this study, we aim to fill this void by investigating different infusion methods that impose external forces on the lubricant. We developed our SLIPS by hot embossing nanostructures onto polypropylene by using molds that were laser micromachined. These textured surfaces were then infused with silicone oil using three different infusion methods: ultrasonication, vacuum, and hydrostatic pressure. We analyzed the wettability and slipperiness of the SLIPS by evaluating the critical tilt angle and comparing the sliding velocities of water droplets on each sample at a tilt angle of 20°. Additionally, the durability of the SLIPS was tested by dropping 50 successive water drops onto the samples and evaluating the droplet-surface interactions throughout. The sonicated infusion method yielded SLIPS that performed the best with a contact angle hysteresis of 13°, a critical tilt angle of 18.3°, a sliding velocity of 1.66 mm/s, and the least accumulation of droplets over time with use. These values are greatly improved when compared to the control sample where lubricant was simply dripped on, which resulted in a contact angle hysteresis of 20°, a critical tilt angle of 26.3°, and a sliding velocity of 0.23 mm/s. The sonicated and drip infusion methods were also compared with different materials (stainless steel) and different textures (microstructures). It was found that the improvement in slipperiness using the sonicated infusion method is prominent for nanoscale textures on both stainless steel and polypropylene. In this study, we discuss the challenges with oil depletion in SLIPS (cloaking and wetting ridges) and with the selection of contact angle measurement methods. While further investigation as to why certain applied forces during infusion yield better SLIPS is warranted, these forces greatly affect the outcome. This work suggests that researchers should consider using sonication or other methods of lubricant infusion that apply external forces as infusion techniques to yield better SLIPS on the nanoscale.

Quantitative signs on ultrasound biomicroscopy images associated with the status of silicone oil emulsification within the eye.

Silicone oil (SO) is a commonly used intraocular tamponade in the treatment of rhegmatogenous retinal detachment (RRD). SO emulsification is a common complication after SO injection. This study aimed to investigate correlations between SO emulsification signs on ultrasound biomicroscopy (UBM) and the real number/size of SO droplets. An observational, cross-sectional study. Thirty-five RRD patients (19 males; 35 eyes) who underwent pars plana vitrectomy and SO injection were enrolled in the study. SO emulsification signs on UBM (endothelial deposits, floating droplets, ghost images, hyperoleon, anterior chamber angle impregnation, anterior iris surface impregnation, posterior iris surface impregnation and ciliary body impregnation) were acquired and quantified two days before SO removal, while real number/size of the SO droplets with a diameter in 0.4-20 μm in the first 2 mL washout fluid collected intraoperatively during SO removal were assessed by Coulter counter. Then the correlations between these values were explored. The grade of tissue impregnation and hyperoleon area in the anterior chamber demonstrated significant correlations with the number of large (5-20 μm) SO droplets (r = 0.336; P = 0.048 and r = 0.350; P = 0.039, respectively); however, no significant correlations were observed with the total number of droplets (0.4-20 μm)or the number of small (0.4-5 μm) droplets (both P ＞ 0.05). The UBM quantitative grade of tissue impregnation and hyperoleon area in the anterior chamber could provide a noninvasive overview of the actual degree of SO emulsification before SO removal surgery.

The silicone depletion in combination products induced by biologics

Silicone oil (SO) migration into the drug product of combination products for biopharmaceuticals during storage is a common challenge. As the inner barrel surface is depleted of SO the extrusion forces can increase compromising the container functionality. In this context we investigated the impact of different formulations on the increase in gliding forces in a spray-on siliconized pre-filled syringe upon storage at 2–8 °C, 25 °C and 40 °C for up to 6 months. We tested the formulation factors such as surfactant type, pH, and ionic strength in the presence of one monoclonal antibody (mAb) as well as compared three mAbs in one formulation. After 1 month at 40 °C, the extrusion forces were significantly increased due to SO detachment dependent on the fill medium. The storage at 40 °C enhanced the SO migration process but it could also be observed at lower storage temperatures. Regarding the formulation factors the tendency for SO migration was predominantly dependent on the presence and type of surfactant. Interestingly, when varying the mAb molecules, one of the proteins showed a rather stabilizing effect on the SO layer resulting into higher container stability. In contrast to the formulation factors, those different stability outcomes could not be explained by interfacial tension (IFT) measurements at the SO interface. Further characterization of the mAb molecules regarding interfacial rheology and conformational stability were not adequately able to explain the observed difference. Solely a hydrophobicity ranking of the molecules correlated to the stability outcome. Further investigations are needed to clarify the role of the protein in the SO detachment process and to understand the cause for the stabilization. However, the study clearly demonstrated that the protein itself plays a critical role in the SO detachment process and underlined the importance to include verum for container stability.

Electroretinograms Recorded with Skin Electrodes from Post-Vitrectomy Silicone Oil Filled Eyes with Proliferative Diabetic Retinopathy.

To determine the physiological status of the retina by electroretinography (ERG) using skin electrodes and the RETevalTM system in eyes that had undergone pars plana vitrectomy (PPV) with silicone oil (SO) tamponade. The vitrectomy was performed for a retinal detachment and proliferative diabetic retinopathy (PDR). Retrospective case series. ERGs were recorded with the RETevalTM system (LKC Technologies Inc. Gaithersburg, MD; Welch Allyn, Inc. Skaneateles Falls, NY) from eight eyes with PDR before and after the SO removal. The amplitudes and implicit times of the a- and b-waves of the ERGs before the SO removal were compared to that after the SO removal. ERGs were recordable in four eyes before and after the SO removal and the a- and b-amplitudes improved in three eyes and worsened in one eye after the SO removal. In the remaining four eyes, ERGs were non-recordable both before and after the SO removal. These results indicate that ERGs picked up by skin electrodes can be used to assess the physiology of the retina in eyes with a SO tamponade. The flat ERGs in the SO-filled eye indicated the presence of diffuse retinal damage which was confirmed by the flat ERGs after the SO removal.

PREMATURE EMULSIFICATION OF SILICONE OIL AFTER RETINAL DETACHMENT REPAIR IN THE SETTING OF HIGH-INTENSITY EXERCISE.

To describe a rare case of silicone oil emulsification that occurred only three months postoperatively. We discuss the implications for postoperative counseling. Retrospective chart review of a single patient. Thirty-nine-year-old woman who presented with a right eye macula-on retinal detachment that was repaired with scleral buckle, vitrectomy, and silicone oil tamponade. Her course was complicated by extensive silicone oil emulsification within 3 months postoperatively, most likely because of shear forces induced by her daily CrossFit exercise regimen. Typical postoperative precautions after a retinal detachment repair include no heavy lifting or strenuous activity for one week. These restrictions may need to be more stringent and long-term for patients with silicone oil to prevent early emulsification.

Thermal management of lithium-ion batteries with direct and counter flow channels: A comparative study of different cooling fluids

The study addresses the crucial issue of thermal management in lithium-ion batteries (LIBs) and the maintenance of safe operational temperatures. It emphasizes the importance of efficient cooling mechanisms in preventing damage. A comparative analysis was conducted to assess the impact of various cooling fluids on the thermal performance of LIBs using direct and counter fluid flow channels. The study involved the use of different cooling fluids including water, water-glycol, Novec7000, mineral oil, and silicon oil. The researchers examined temperature variation, surface Stanton number (SN), surface Nusselt number (Nu), surface heat transfer coefficient (HTC), battery surface temperature, and pressure drop to evaluate the battery cooling process with different cooling configurations. The battery cooling part proved highly effective in managing heat, achieving a significant maximum temperature reduction of 30.70 % and 37.43 % for direct and counter flow channels, respectively. The Nu values of various fluids showed notable differences, with water-glycol showing a 3.76 % increase, Novec 7000 with an 11.39 % increase, mineral oil with a 15.46 % improvement, and silicon oil with a 20.09 % increase. The HTC values in the direct flow channel proved a consistent decrease from 16.09 to 57.73 to 11.07–25.69 W/m2K, respectively. Similarly, the HTC values for the counter flow channel ranged from 15.88 to 55.38 to 11.07–25.69 W/m2K. Additionally, it was seen that silicon oil outperformed other cooling fluids with a 6.0 % improvement in HTC in both direct flow and counter flow channels. The SN showed increases of 17.34 %, 20.11 %, 26.76 %, 29.57 %, and 29.60 %, respectively, at all five liquid flow velocities through the direct channel, and 19.39 %, 22.18 %, 28.34 %, 36.58 %, and 37.64 %, respectively, through the counter flow channel. These findings clearly show the superior heat transfer capabilities of silicon oil compared to other coolants. However, it is important to note that the use of silicon oil also resulted in a lower pressure drop, a critical consideration for ensuring efficient cooling. These findings have significant implications for the advancement of battery thermal management systems for electric vehicles, as designers can optimize the cooling process by considering different cooling configurations to enhance the thermal performance of battery packs while ensuring safe and stable operation.

Optimized design of silicone oil torsional damper for diesel generator

Abstract Due to the high cylinder pressure and high-performance requirements, the silicone oil damper of an inline six-cylinder diesel generator needs to be optimized to reduce the crankshaft stress. The centralized mass method was used to simplify the crankshaft system. A multi-body dynamic model was established, and the crankshaft stress and torsional vibration amplitude were simulated. The results show that the excessive shear stress at generator crank pin 5 is due to the resonance between the first-order intrinsic frequency of the shaft system and the 3rd harmonic torsional vibration. The shear stress was analyzed for different damper thicknesses and stiffnesses, and it was found that the shear stress at crank pin 5 was minimized when the damper thickness was 60 mm and the torsional stiffness was 250,000 N·m/rad. The torsional amplitudes at different speeds and frequencies were measured in the bench test, and the results were consistent with the calculations. The designed silicone oil torsional damper meets the requirements of the 2000-hour bench test.

Subretinal inverted hypopyon: Emulsified silicone oil in long-standing silicone oil tamponade

Subretinal inverted hypopyon: Emulsified silicone oil in long-standing silicone oil tamponade

Study on heat dissipation of torsional vibration damper for engine crankshaft

Abstract High temperatures in torsional vibration dampers can cause silicone oil to fail, increasing crankshaft vibration and shortening component fatigue life. Accurate prediction of the damper temperature field is key to the manufacture of highly reliable torsional vibration dampers. This study establishes the relationship between temperature, torsional vibration amplitude, silicone oil viscosity, rotational speed, housing and inertia ring clearance, and heat generation power based on Comsol. A bench test was carried out on a 6-cylinder inline diesel engine. The simulated temperature profile matched the tested result in terms of trend and relative value, and the established model could accurately predict the temperature field of the engine crankshaft torsional vibration damper.

Primary Internal Limiting Membrane Peel and Its Effects on Epiretinal Membrane After Pars Plana Vitrectomy for Rhegmatogenous Retinal Detachment

Purpose: To determine the effect of internal limiting membrane (ILM) peel in post-operative development of epiretinal membrane and to see visual outcomes of patients undergoing pars plana vitrectomy with and without ILM peel. Study Design: Quasi experimental study. Place and Duration of Study: Retina clinic of Al-Ibrahim Eye Hospital from July, 2022 to Dec, 2022. Methods: A total of 60 eyes which underwent pars plana vitrectomy (PPV) with silicone oil for Rhegmatogenous retinal detachment (RRD) were included. Patients with previous vitreoretinal surgery or ocular trauma, macular diseases or coexisting conditions that could affect the outcomes or complicate the surgery were excluded. Group A included patients with ILM peel and Group B included patients with no ILM peel (30 eyes each). Frequency was calculated for gender, epiretinal membrane formation. and was compared between both groups using chi square. Results: Mean age in group A was 47.63 ± 8.61 years and in group B was 45.36 ± 6.63 years. Gender distribution showed 66.6% males in group A and 43.3% in group B. After 3 months the group A had significantly lower frequency of ERM formation (3.33%) as compared to group B (16.67%) with p &lt;0.05. However, post operativevisual acuity was not significantly different between the two groups (p &gt; 0.05). Conclusion: This study shows that primary ILM peel diminishes the development of ERM and decreases the need for second surgical procedure. However, postsurgical visual acuity between the two groups showed no significant difference.

A challenging case of scleral buckle-related restricted strabismus with unexpected good postoperative outcomes: A case report

Abstract Strabismus surgery in a scleral buckle patient is a challenging task that requires precise planning and meticulous surgical skills to accomplish a successful outcome. We report a case of a 32-year-old male who presented with complaints of diminution of vision in the right eye (RE) for 23 years and outward deviation of RE for 5 years after blunt trauma with a ball. The patient was diagnosed with RE total retinal detachment (RD) with traumatic retinal dialysis. He underwent scleral buckling as RD surgery in 2004 followed by silicon oil removal 6 months later elsewhere. On ocular examination of the RE, the best corrected visual acuity was perception of light with accurate projection of rays in all four quadrants, there was grade III relative afferent pupillary defect with an exotropia of 20° on Hirschberg test. The prism bar reflex test revealed an exotropia of 50 prism diopters (PD) [Figure 1]. An anterior segment examination revealed posterior subcapsular and cortical cataracts. After taking a retina clinic opinion, the patient underwent uneventful RE cataract surgery with in-bag implantation of a foldable implant cataract surgery first, followed by strabismus surgery under a guarded visual prognosis. Clinically significant adhesion and the presence of the scleral buckle posed a magnificent challenge during the strabismus surgery. The plan was improvised to 8 mm lateral rectus recession with 4 mm hang loose recession irrespective of a large deviation under local anesthesia. To our surprise, a satisfactory primary position alignment within 10 PD (orthophoria) was achieved, which was maintained on subsequent follow-up visits. We report an interesting and challenging case of restrictive strabismus due to scleral buckle which emphasizes that surgical procedures and their outcomes may not always align with expectations. Therefore, it is necessary to adopt a flexible and customized approach to effectively manage such instances.

Double-Arc Slow-Coagulation Transscleral Cyclophotocoagulation Laser Protocol: One-Year Effectiveness and Safety Outcomes

To report the short-term efficacy and safety results of a new continuous laser protocol, double-arc slow-coagulation transscleral cyclophotocoagulation (DA-TSCPC). Multicenter retrospective study. Refractory glaucoma patients that had undergone DA-TSCPC between April 2019 and July 2022, with at least 12 months of postoperative follow-up, were consecutively enrolled. The technique was standardized (energy: 1400mW; duration: 4s; 28 applications). The applications were divided into 2 rows (upper and lower arcs). For each arc, 7 spots were applied over the ciliary body shadow and 7 spots 1.5mm behind, sparing the 3 and 9 o'clock meridians. Success was defined as postoperative intraocular pressure (IOP) between 6 and 18 mmHg, and an IOP reduction of 30% (without oral acetazolamide). For eyes with no light perception (NLP), in which treatment goal was pain relief, success was defined as a 30% IOP reduction and no pain (without oral acetazolamide). Patients were divided according to visual acuity: ≥20/400 (group 1) and <20/400 (group 2). Ninety eyes of 90 patients (mean age: 61±15 years) were included. Glaucoma diagnosis frequency was: neovascular glaucoma (38%), open-angle glaucoma (28%), silicone oil secondary glaucoma (17%) and others (18%). Overall, the mean IOP was significantly reduced from 35±12 to 22±14 mmHg (p<0.01) at the last follow-up visit. The number of hypotensive eye drops (2.6±1 to 2.3±1; p=0.02) and the use of oral acetazolamide (61% to 11%; p<0.01) were also reduced. Kaplan-Meier survival analysis revealed a global success rate of 65.6% after 12 months. A higher success rate was found for group 1 (78.6%) compared to group 2 (59.6%; p=0.047; logrank test). The main complications observed were corneal ulcer (4.4%), macular edema (1.1%) and hyphema (1.1%). Among the 26 eyes with NLP, 65% achieved success criteria at 12 months and 2 (7.7%) developed phthisis. Based on these initial retrospective data, the DA-TSCPC protocol seems to be an alternative for refractory glaucoma management, presenting significant IOP reduction and a good safety profile after one year. Better outcomes were observed in eyes with less severe functional damage.

Resolution of diabetic macular edema following silicone oil removal

Resolution of diabetic macular edema following silicone oil removal

Development of Oil Vehicle Screening Method for Bromo Acid Dye-Based Color-Changing Cosmetic Formulation

Bromo acid dye (Red 21) recently gained attention in the production of color-changing cosmetics. The critical aspect in the development of cosmetic products using this dye group is the compatibility of its oil vehicles. The compatibility of bromo acid dyes with oil vehicles is determined by several parameters such as the dye solubility in the oils, clarity of the mixture, and the ability to change color when the pH of the solution is adjusted to match the skin’s pH. Therefore, this study conducted the compatibility study by examining the ability of 27 oil samples to dissolve Red 21. The ability of a vehicle to dissolve a compound is influenced by the polarity of the vehicle. Hence, a correlation was established between the relative polarity of oils and their ability to dissolve Red 21. The results showed that the water-oil interfacial tension was negatively correlated (r = -0.64) with Red 21 solubility in the oil. From this research, the water-oil interfacial tension represented the relative polarity of the oil and was considered sufficient to predict the compatibility of the oil with Red 21. In addition, hydrocarbon and silicone oils are not compatible with Red 21.

Assessment of ansys-fluent Code for Computation of Two-Phase Flow Characteristics: A Comparative Study of Water–Air and Silicone Oil–Air in a Vertical Pipe

Abstract The study aimed to assess the flow characteristics of water–air and silicone oil–air in a vertical upward pipe, utilizing computational fluid dynamics (CFD) simulations with the volume of fluid (VOF) model. Structured meshes with various resolutions were employed to ensure mesh independence, and the k–ε realizable model addressed turbulence. Simulations were conducted in a vertical pipe with a diameter of 67 mm, while varying superficial gas velocities. The investigation focused on the impact of superficial gas velocity on flow patterns, radial void fractions, void fraction time series, probability density functions (PDFs), and mean void fractions. Results indicated a transition in flow patterns with increasing superficial gas velocities: water–air shifted from cap-bubbly to churn flow, and silicone oil–air transitioned from bubbly to annular flow. Notably, annular flow was observed in silicone oil even at low gas velocity. Substantial alterations were observed in radial void fraction profiles corresponding to changing flow patterns. Void fraction time series showed higher fluctuations for water compared to silicone oil, and PDFs identified regimes. Mean void fraction consistently demonstrated higher values for silicone oil compared to water across all flow conditions. The CFD results were validated against experiments, demonstrating good agreement. Furthermore, the validated model was applied to predict pressure drops and liquid velocities between the two systems. Silicone oil exhibited lower pressure drops compared to water. Significant differences in liquid velocities were observed between the two systems at 0.05 m/s and 5.71 m/s, emphasizing the impact of fluid properties.