Maximum Spread Research Articles

Dynamic behavior of droplet impact on micro-nano structures with extreme wetting properties

Extreme wetting surfaces represented by superhydrophilic and superhydrophobic surfaces have important applications in heat transfer engineering such as boiling and condensation. The droplet impact behavior is helpful to deepen the understanding of extreme wetting characteristics and guide practical engineering applications. In this study, superhydrophilic and superhydrophobic micro-nano structures were fabricated by micro embossing and subsequent chemical treatment, and the droplet impact dynamics of microstructures, nanostructures, and micro-nano structures were analyzed using water and alcohol. Alcohol has the lower surface tension and wets the fabricated surfaces more easily than water. Among all fabricated structures, micro-nano multiscale structures exhibit the most extreme droplet impact dynamics. Whether it is water or alcohol droplets, the superhydrophilic micro-nano structures show the best spreading properties, and the maximum spreading factor (the ratio of the droplet wetting diameter to the initial diameter) of water is 134.1 % higher than the flat surface, which is also higher than both the microstructures and the nanostructures. Water droplets are more likely to bounce after impacting the superhydrophobic micro-nano structures than flat and nanostructures. However, due to the pinning effect of the larger-scale microstructures, the droplets impact on micro-nano structures would break and splash while the Weber number exceeds 43.41. The high-temperature impact dynamics show that the superhydrophobic micro-nano structures has excellent high-temperature resistance and can fully bounce within the tested range. The superior bouncing properties indicates the excellent condensation potential of the superhydrophobic micro-nano structures. The superhydrophilic micro-nano structures will be beneficial to enhance boiling heat transfer engineering applications, and the boiling heat transfer of droplets on the superhydrophilic micro-nano structures is the most severe during the boiling temperature range, and the drying time after alcohol impact is ∼ 63.4 % shorter than that of the superhydrophobic micro-nano structures.

An Experimental Study on Complete Droplet Rebound from Soft Surfaces: Critical Weber Numbers, Maximum Spreading, and Contact Time.

Droplet impact on soft surfaces (PDMS) was experimentally studied with particular interest in the complete rebound of droplets. This study focuses on the effect of liquid viscosity and the elastic modulus of the substrate on the critical rebound Weber number, maximum spreading, and contact time. Specifically, the lower and upper critical Weber numbers increase with an increasing droplet viscosity. With decreasing PDMS elastic modulus, the upper critical Weber number increases, while the lower critical Weber number decreases. The PDMS elastic modulus does not significantly affect the maximum spreading time and contact time. An interesting phenomenon of discontinuous contact time was experimentally observed and was theoretically interpreted.

Influence node analysis based on neighborhood influence vote rank method in social network

Social Networks are used for various purposes like advertising, product launches, sentiment analysis, opinion mining, and event detection etc. Terrorist targets social network users to spread the terrorism. Influence analysis is used in social networks to find the influence of users and the impact of the messages, mainly for advertising. In this research, the Neighborhood Influence – Vote Rank (NI-VR) method is proposed to analyze the terrorism and social network datasets temporally to find the influence node in Social networks. The Global Terrorism Dataset (GTD) was used to analyze the terrorism activity and temporal analysis on Social Network data to find the influence node. The Neighborhood node influence is measured and considered in the Social Network data to effectively find the influence node. The nodes’ vote score and vote ability were measured to rank the nodes based on influence. The neighborhood influence is measured to update the vote score and vote ability based on influence value. The neighborhood influence method is applied to rank the node has the advantage of analyzing the probability of affected nodes and recover nodes that help to effectively find the influence nodes. The outcomes illustrate that the proposed NI-VR achieved a maximum spread influence of 843 and the existing Greedy method has a higher spread influence of 840 in influence node analysis.

OFFSET COALESCENCE BEHAVIOR OF IMPACTING LOW-SURFACE TENSION DROPLET ON HIGH-SURFACE-TENSION DROPLET

The impact of droplets of varying surface tension and subsequent spreading over a solid surface are inherent features in printing applications. In this regard, an experimental study of the impact of two drops of varied surface tension is carried out where the sessile water droplet on a hydrophilic substrate is impacted upon by another droplet of sequentially lowered surface tension. The impacts are studied for different impact velocities and offsets with respect to the mid-plane of the two colliding droplets. Sodium dodecyl sulfate is used to: (i) alter the surface tension without altering the viscosity, (ii) study the various parameters affecting the spreading length viz. the surface tension, (iii) offset between the drops, and (iv) impact velocity. The spreading lengths are obtained through image processing of the captured footage of the impact dynamics by a high-speed camera. It is found out that upon lowering the surface tension, the maximum and equilibrium spreading length varies to a significant extent, and the nature of the spreading dynamics changes. Both side- and top-view imaging are performed to understand the overall hydrodynamics. There is also a substantial change in "drawback" when dissimilarity in surface tension between the impacting droplets exists. Finally, a fit model is obtained to predict the maximum spread length of the various cases.

Microgel particle deposition patterns after impinging on nanofiber-based coatings

The study focuses on predicting the hydrodynamics of sodium alginate-based microgel “liquid core–gel shell” particles for droplet-based bioprinting. Hydrophobic polytetrafluoroethylene nanofiber-based coating (NBC #1) and hydrophilic polycaprolactone–polyvinylpyrrolidone NBC #2 are manufactured to serve as the basis for microgel deposition. An approach is proposed to model the flow of a Maxwell gel-like liquid with different fluidity, surface tension, and initial velocity along an inhomogeneous interface after microgel particle–NBC collision. Wetting and anti-wetting pressure differences allow estimating liquid impalement into NBCs at We = 10–50. For NBC #2, the initial particle velocity plays mainly a decisive role in predicting the contact diameter and height at maximum spreading and receding. For NBC #1, the pinning is considered by introducing the complex parameter resolving particle inertia, microgel rheology and surface tension, and NBC characteristics. The flow along the porous interface physically correlates with the extended Freundlich model, explaining the surface inhomogeneity caused by multilayer adsorption.

Estimation of Photon Path Length and Penetration Depth in Articular Cartilage Zonal Architecture Over the Therapeutic Window.

The key characteristics of light propagation are the average penetration depth, average maximum penetration depth, average maximum lateral spread, and average path length of photons. These parameters depend on tissue optical properties and, thus, on the pathological state of the tissue. Hence, they could provide diagnostic information on tissue integrity. This study investigates these parameters for articular cartilage which has a complex structure. We utilize Monte Carlo simulation to simulate photon trajectories in articular cartilage and estimate the average values of the light propagation parameters (penetration depth, maximum penetration depth, maximum lateral spread, and path length) in the spectral band of 400-1400 nm based on the optical properties of articular cartilage zonal layers and bulk tissue. Our findings suggest that photons in the visible band probe a localized small volume of articular cartilage superficial and middle zones, while those in the NIR band penetrate deeper into the tissue and have larger lateral spread. In addition, we demonstrate that a simple model of articular cartilage tissue, based on the optical properties of the bulk tissue, is capable to provide an accurate description of the light-tissue interaction in articular cartilage. The results indicate that as the photons in the spectral band of 400-1400 nm can reach the full depth of articular cartilage matrix, they can provide viable information on its pathological state. Therefore, diffuse optical spectroscopy holds significant importance for objectively assessing articular cartilage health. In this study, for the first time, we estimate the light propagation parameters in articular cartilage.

A Semidefinite Programming Method Weighted Sum Based for Solving a Multi-area Emission (Environmental) Economic Dispatch Problem

This paper presents a semi-definite programming (SDP) optimisation approach for solving multi area, emission/economic dispatch (MAEED) problems in thermal power systems. The multi-objective problem was transformed into matrix form as an SDP relaxation problem and subsequently solved with a MATLAB programming suite. The system inequality and equality constraints were entered into a Self-Dual Minimisation (SeDuMi) parser. Simulations were tested on four (4) IEEE benchmark models to validate the efficiency of the proposed SDP method. However, in the generation of the Pareto-fr ont solutions, ideal minimum points were used in the determination of the maximum spread out of the Pareto solutions by the algorithm. This involves the use of a standard weighted sum method in generating the Pareto-optimal solution between two objective functions. Twenty-one (21) runs were carried out for the parameter value to explore the effect of control weight selection k1. A comparative study demonstrated the effectiveness of tie-line constraint and without tie-line constraint, respectively on the optimi sation model for the power dispatch problems solved by using the proposed SDP approach. The optimisation results for the minimum fuel cost using the SDP approach for the case when a tie-line constraint is included was US$ 2,151.7 /hr with minimum emission of 3.4687 Ton/hr. This is lower than US$ 2,162.2 /hr with minimum emission of 3.6662 Ton/hr obtained when the tie-line constraint is not included in the optimisation model on IEEE four-area, sixteen network. Additionally, the comparative results with all other methods reported in the literature for different test cases were also presented in this paper. Lower operational costs were obtained for both tie-lines and no tie-lines power transfer cases, showing that the SDP method performed well in accuracy compared to other methods. The SDP method was employed in this research to deal with the multi-area emission economic power dispatch problem due to its inherent advantages in achieving a global optimal solution and, this approach would also assist the power administrator to come up with an improved decision making in attaining an optimum power dispatch of power generation.

Spreading dynamics of a droplet upon impact with a liquid film containing solid particles.

This study examines how a deionized water droplet behaves when it centrally collides with a liquid film containing TiO2 nanoparticles at low impact velocities, aiming to understand how nanoparticles affect droplet spreading, in particular its maximum spreading diameter. Typically, we found that both the spreading velocity and dynamic contact angle of the droplet would be similarly affected by increasing TiO2 nanoparticle concentration. During retraction, the droplet's dimensionless spreading diameter oscillates, with more pronounced oscillations at higher nanoparticle concentrations. Moreover, both the droplet's maximum dimensionless rebound height and dynamic contact angle show similar trends with increasing TiO2 nanoparticle concentration. Interestingly, we proved that the influence of the solid-liquid interaction (Stokes force) on the fluid during the spreading process accounts for less than 2% of the surface energy when the droplet reaches its maximum spreading diameter, indicating a negligible effect on droplet spreading. We hypothesize that the droplet's initial energy is fully converted into surface energy and viscous dissipation at maximum spreading diameter, which involves viscous dissipation both between the fluid and the solid wall surface and the fluid and solid particle surface. Based on this, we developed a model for predicting the droplet's maximum spreading diameter that includes parameters associated with the solid particles. Compared to models in the literature that do not consider the effect of solid particles, our model aligns more closely with experimental data. The results indicate that adding solid particles leads to increased viscous dissipation, which in turn reduces the droplet's maximum spreading diameter.

Impact of Nano-Dap on Growth and Development of Cabbage

The current study, "Impact of nano-DAP on growth and development of cabbage," was carried out in 2021–2022 at the Department of Horticulture's Experimental Farm at A.A.U., Jorhat. RBD was used to set up the study. The treatments followed were T1 (Untreated control), T2 (100% RDF of N & K), T3 (100% RDF of 130:80:80 kg/ha), T4 (T2 + ST with nano-DAP @ 5 ml/ltr), T5 (T2 + ST@ 10 ml/ltr), T6 (T2 + 1 FS of nano-DAP @ 6 ml/ltr at 25-30 DAT), T7 (50 % P, 100% N & K + FS nano-DAP @ 2 ml/ltr at 25-30 DAT), T8 (25% P, 100% N & K + FS nano-DAP @ 4 ml/ltr), T9 (T2 + ST @ 5 ml/ ltr + FS nano-DAP @ 6 ml/ltr), T10 (25% P, 100% N & K + ST @ 5 ml/ ltr + FS nano-DAP @ 4 ml/ltr), T11 (50% P, 100% N & K + ST @ 5 ml/ ltr + FS nano-DAP @ 2 ml/ltr), T12 (25% P, 50% N & 100% K + ST @ 5 ml/ ltr + FS nano-DAP @ 4 ml/ltr) and T13 (50% P, 50% N & 100% K + ST @ 5 ml/ ltr + FS nano-DAP @ 2 ml/ltr).
 Investigation was done comparing the results of the nano-DAP treatments with the suggested fertilizer dosage. The results revealed that the maximum plant spread and number of non-wrapper leaves was observed in T3 (17.12 cm) and (7.67) at 30 DAT whereas in T3 (34.77 cm) and (16.83) at 60 DAT.The highest leaf area was recorded in T3 (107.56 sqcm) at 30 DAT and at 60 DAT (226.54 sqcm), although at 30 DAT, the maximum leaf fresh weight was recorded in T7 (4.40 g) although in T3 (12.46 g) at 60 DAT. The maximum number of days (88.30 days) to harvest was taken by T5. Thus, the investigation suggests that nano-DAP can reduce the amount of inorganic fertiliser applied while maintaining the potency of the crop.

The role of viscoplastic drop shape in impact

The impact of fluid drops on solid substrates is a cardinal fluid dynamics phenomenon intrinsically related to many fields. Although these impacting objects are very often non-spherical and non-Newtonian, previous studies have mainly focused on spherical Newtonian drops. As a result, both shape and rheological effects on the drop-spreading dynamics remain largely unexplored. In the present work we use a mixed approach combining experiments with multiphase three-dimensional numerical simulations to extend the work reported by Luu & Forterre (J. Fluid Mech., vol. 632, 2009, pp. 301–327) by highlighting the fundamental role of shape in the normal impact of viscoplastic drops. Such complex fluids are highly common in various industrial domains and ideally behave either like a rigid body or a shear-rate-dependent liquid, according to the stress solicitation. Spherical, prolate, cylindrical and prismatic drops are considered. The results show that, under negligible capillary effects, the impacting kinetic energy of the drop is dissipated through viscoplastic effects during the spreading process, giving rise to three flow regimes: (i) inertio-viscous, (ii) inertio-plastic, and (iii) mixed inertio-visco-plastic. These regimes are deeply affected by the drop initial aspect ratio, which in turn reveals the possibility of using drop shape to control spreading. The physical mechanisms driving the considered phenomenon are underlined by energy budget analyses and scaling laws. The results are summarised in a two-dimensional diagram linking the drop maximum spreading, minimum height and final shape with different spreading regimes through a single dimensionless parameter, here called the impact number.

Non-Axisymmetric Bouncing Dynamics on a Moving Superhydrophobic Surface

The phenomenon of droplet impact on moving surfaces is widely observed in fields such as transportation, rotating machinery, and inkjet printing. Droplets exhibit non-axisymmetric behavior due to the motion of solid surfaces which significantly determines core parameters such as contact time, maximum spreading radius, and bounding velocity, thereby affecting the efficiency of related applications. In this study, we focus on the kinetics and morphology of the non-axisymmetric bouncing behaviors for droplets impacting on a moving superhydrophobic surface (SHPS) within the normal (Wen) and tangential (Wet) Weber numbers. Considering the influences of the moving surface on the contact area and contact time, the previous scaling formula for the horizontal velocity of droplets has been improved. Based on the velocity superposition hypothesis, we establish a theoretical model for the ratio of the maximum spreading radius at both ends depending on Wen and Wet. This research provides both experimental and theoretical evidence for understanding and controlling the non-axisymmetric behavior of droplets impacting on moving surfaces.

Dynamic behavior of droplet impacting on a moving surface

The research specifically analyzes the characteristics of the impacting droplet and its behavior on the moving surface. The experimental results demonstrate that the droplet impact can be divided into two stages: spreading and stretching. The surface shear force is found to play a decisive role in the droplet's dynamic behaviors. Specifically, the surface shear force inhibits liquid fingers at the front edge of the liquid film during the spreading stage, but promotes the extension of liquid fingers at the trailing edge of the droplet during the stretching stage. The surface shear force has a significant influence on the longitudinal spreading factor of the droplet during the spreading stage. The transverse maximum spreading time decreases with the increase of shear weber number. The wake flow of the droplet is mainly divided into four types: wetting deposition, fracture separation, single finger, and multi-fingers. Additionally, the ratio of the horizontal maximum spreading factor to the longitudinal spreading factor in the same time is found to be positively correlated with the ratio of the two weber numbers. The research findings contribute to the fundamental understanding of droplet dynamics on moving surfaces and highlights the importance of considering surface shear force in understanding droplet dynamics and provides a basis for further research in this field.

NUMERICAL INVESTIGATION OF TURBULENCE CHARACTERISTICS AND SELF-SIMILARITY IN A HIGHLY AERATED STABLE HYDRAULIC JUMP USING LARGE EDDY SIMULATION

This work presents a numerical study of a stable hydraulic jump at Froude number 4.25 and Reynolds number 1.15×105 inside a horizontal and rectangular channel with a length of 3.2 m, a width of 0.5 m and a height of 0.4 m using large eddy simulation (LES). Classical hydraulic jump characteristics are obtained, such as conjugate depths, jump length, void fraction and velocity profiles. The hydraulic jump maximum streamwise velocity decay and shear layer spreading rate are simulated and compared with experimental data. For these parameters, numerical results demonstrate that is possible to stablish an analogy with other shear flows, such as the horizontal plane wall jet. Profiles of streamwise and vertical components of mean velocity are simulated, and self-similarity is observed for cross-sections located at the recirculation region of the jump. Self-similarity is also observed in terms of turbulent fluctuations, insofar as LES simulations indicate a high level of turbulence in the recirculation region. The simulated root mean square of streamwise velocity fluctuations, , ranges from 0.5 to 0.7 of the maximum cross-sections velocity, whereas the root mean square of vertical component of velocity fluctuations, , stays around 0.5 of the maximum cross-sections velocitiy. All validation comparisons show good agreement with the selected experimental data of Kramer and Valero (2020) and Wang (2014), presenting average deviations always lesser than 5%.

A bi-objective low-carbon economic scheduling method for cogeneration system considering carbon capture and demand response

Carbon capture and storage (CCS), energy storage (ES), and demand response (DR) mechanisms are introduced into a cogeneration system to enhance their ability to absorb wind energy, reduce carbon emissions, and improve operational efficiency. First, a bi-objective low-carbon economic scheduling model of a cogeneration system considering CCS, ES, and DR was developed. In this model, the ES and CCS remove the coupling between power generation and heating. The DR mechanism, which is based on the time-of-use electricity price and heating comfort, further enhanced the flexibility of the system. In addition, an improved bare-bones multi-objective particle swarm optimisation (IBBMOPSO) was designed to directly obtain the Pareto front of the low-carbon economy scheduling model. The particle position update mode was improved to balance global and local search capabilities in various search stages. The Taguchi method was used to calibrate the algorithm parameters. The inverse generational distance (IGD), hypervolume (HV), and maximum spread (MS) were used to evaluate the distribution and convergence performance of the algorithm. The improved technique for order preference by similarity to an ideal solution (TOPSIS) method was utilised to obtain the optimal compromise solution. Finally, the proposed method was tested on a cogeneration system in Northeast China. According to the comparison results, the average economic cost of the cogeneration system considering CCS, ES, and DR was reduced by approximately 1.13%, and carbon emissions were reduced by 6.79%. The IBBMOPSO is more competitive than the NSGA-II, MOWDO, MOMA, MOPSO, and BBMOPSO in low-carbon economic scheduling for the cogeneration system.

Droplet impact dynamics on a flexible superhydrophobic cantilever wire mesh

Droplet impact on fixed permeable surfaces has many applications, including spray formation, coating deposition, and filtration processes. The present research studies the droplet and beam dynamics during the water droplet impact on the flexible superhydrophobic cantilever mesh, and the results are compared with the impact on a fixed-fixed superhydrophobic mesh. The effects of beam flexibility (droplet impact point), mesh opening size, and impact velocity on the rebound behavior of droplets, spreading diameter, contact time, beam deflection, and frequency were investigated. Although the contact time is reduced compared to the rigid surface, the well-known pancake rebound is not observed anymore on the cantilever beam. Therefore, the contact time reduction is not as pronounced as the fixed mesh for the cantilever beam. The spreading time and maximum spreading diameter decreased as the impact distance from the fixed point increased due to the reduced transmitted energy to the beam. However, the retraction time is affected by both beam dynamics and liquid penetration. Therefore, the shortest contact time depends not only on the oscillation and frequency of the beam and droplet but also on the liquid penetration. Moreover, the results prove that by defining an appropriate maximum spreading ratio, it becomes independent of the impact point. Finally, the beam deflection and frequency, in addition to the maximum spreading diameter of the droplet are modeled theoretically.

Predicting Impact Outcomes and Maximum Spreading of Drop Impact on Heated Nanostructures Using Machine Learning.

Accurate prediction of droplet behavior upon impact on a heated nanostructured surface is vital for various industrial applications. In this study, we leverage multiple data-driven machine learning (ML) techniques to model the impact outcome and droplet spreading, employing existing experimental data. Our approach incorporates a comprehensive range of critical control parameters, such as the impact velocity (V), surface temperature (Ts), nanopillars' packing fraction (ϕ), and surface roughness (r). We obtain optimal results when utilizing the artificial neural network classification (ANNC) to construct a phase diagram that encompasses all of the experimental impact behaviors. Additionally, we utilize the support vector regression (SVR) method to model the maximum spreading factor (βmax) as a function of the Weber number (We), defined as the ratio of droplet kinetic to surface energy, and Ts for each surface combination. Consistent with previous experimental observations, our results illustrate that nanostructures not only introduce distinct impact behaviors, such as central jetting, but also influence the boundaries among the deposition, rebound, and splashing regimes within the phase diagram. An increase in ϕ at a constant r promotes deposition and spreading events, while increasing r at a constant ϕ results in enhanced heat transfer to promote the Leidenfrost effect for the rebound regime and a greater disturbance of the liquid lamella to trigger splashing. The SVR prediction reveals the existence of a We-number threshold governed by the nanostructure parameters. Beyond this threshold, the maximum spreading factor (βmax) of a spreading droplet becomes independent of the surface temperature (Ts) as We increases, suggesting that fluid properties are likely the dominating factors influencing the spreading dynamics in the extreme We range.

Interaction between droplet impact and surface roughness considering the effect of vibration

Droplet impingement is pivotal in several fields, such as agricultural spraying, ink printing and firefighting. Although droplet impact studies have received much attention, the combined effects of roughness and vibration on droplet dynamics still need to be explored. In this study, an in-depth analysis is carried out to address this issue, and high-speed photography is utilised to explore the droplet impact process under different roughness and vibration conditions. The results show that higher surface roughness dissipates the kinetic energy of droplet spreading, thus inhibiting droplet spreading. Conversely, vibration imparts additional inertial effects to the droplet, leading to sustained oscillations once the droplet stabilises, which in turn results in a more pronounced variation in the droplet's dynamic contact angle. Therefore, in this paper, the vibrational Weber number (Wev) is employed to characterise the interaction between the vibration-induced extra inertia force and the droplet's surface tension. Moreover, as the Wev increases, the relative velocity of the droplet impact also rises, further intensifying the droplet's spreading behaviour. At a Wev of 8.72 and a surface roughness of 0.4 μm, droplet spreading is enhanced by 33%. While at a surface roughness of 6.3 μm, droplet spreading was suppressed by 32% relative to a surface roughness of 0.4 μm. Ultimately, an empirical model was proposed to predict the droplets' maximum dimensionless spreading coefficient (βmax) under vibration conditions, with an error of ±9.5% in the model prediction. This study delves into the dynamic characteristics of droplets under the combined influence of surface roughness and vibration, offering crucial theoretical foundations and profound insights for engineering applications in the field.

Droplet impact and freezing dynamics on ultra-cold surfaces: A scaling analysis of central-concave pattern

Understanding the freezing of impact water droplets on cold surfaces is of both fundamental and practical significance. Using the VOF (Volume of Fluid) method with the dynamic contact angle and Solidification/Melting models embedded, we simulate the impact and freezing processes of water droplets on ultra-cold surfaces, which extends the surface temperature from about –50 °C previously to –100 °C. Two distinct freezing morphologies of central-pointy or central-concave patterns are obtained and mapped at various surface temperatures and Weber numbers. An inner valley and an outer rim typically form the central-concave pattern. The influence of the surface temperature on the spreading of the contact line is greater than that of the valley. The maximum spreading factors of the contact line and the valley are related to the effective Reynolds number by a 1/3-power law and the Weber number by a 1/4-power one. Furthermore, a theoretical model incorporating the freezing dynamics and the shrinking of the valley is proposed to predict the spreading factors and freezing times of the valley and rim for the central-concave pattern, yielding a global maximum deviation of 20 %. Our results and analyses provide an insight into the coupling mechanism of the droplet impact and freezing dynamics on ultra-cold surfaces.

Impact behaviors of a single aqueous solution droplet on curved surface filler

Chemical absorption is one of the main methods for capturing and absorbing CO2 in post-combustion flue gases. The impact behaviors of the absorbent droplets on the filler have significant effects on CO2 absorption as the absorbent is sprayed down. However, the driving mechanisms behind these behaviors are not fully understood due to the increased difficulty in the absorption tower. In the present study, we numerically investigate the impact behavior of the CO2 absorbent droplet on the curved surface filler. The developed three-dimensional model is validated by our experimental results and previous studies. The driving mechanisms are revealed by focusing on the velocity and pressure field in different stages. The influence of the surface curvature and Weber number is analyzed, with particular attention to the evolution velocity. The liquid film oscillation is characterized by its amplitude and time for different surface hydrophobicity. The results show that the spreading of the liquid film is primarily influenced by the initial inertia, while its retraction and oscillation are mainly controlled by the surface tension and viscosity, leading to a longer retraction and oscillation time. Both pressure and velocity, as well as their peaks, exhibit different distributions depending on the behaviors in different stages. This is similar to the formation of the surrounding air vortex with its center above the gas–liquid interface in different stages. Both the Weber number and the curvature have little effect on the average spreading velocity, whereas the dimensionless maximum spreading diameter vs the Weber number follows a power law dependence. The results are helpful for understanding the physical mechanisms behind the impact behaviors of the CO2 absorbent droplets on the curved surface filler.

ESTIMATION OF AQUFER TRANSMISSIVITY FOR TYPICAL OIL PRODUCING COMMUNITIES OF WESTERN NIGER DELTA USING ELECTRICAL RESISTIVITY SURVEY

Geophysical electrical resistivity method (Vertical Electrical Sounding) using Schlumberger configuration was employed to investigate subsurface formations and aquifer transmisivity in Agbarotor, Agbarha-Otor and Edoiede Agbarha-Otor in Ughelli North Local Government Area in Delta State, Southern Nigeria with VES evenly carried out in the aforementioned study areas. ABEM Signal averaging system (SAS) 1000 Terrameter, was one of the major equipments used in obtaining the resistivity field data with a maximum current electrodes spreading of 500m done with the aid of a tape. The interpretation of the data gotten from the field was done using WINRESIST software coupled with the qualitative and quantitative curve matching to obtain modelize parameters and curves type for various VES points. The model parameters displayed up to six formations layers which include topsoil, laterite, clay and sand (fine, medium and coarse) formation. The resistivity of the confined aquifer ranges from 1037.6-4986.5Ωm with thickness varying interval of 16.3m and 42.9m. The investigation denote that VES 1 of Agbarotor, VES 6 for Agbarha-Otor and VES 7,9,10 of Edoiede Agbarha-Otor are the best locations for citing boreholes in the studied areas since they are characterize with higher resistivity (low corrosivity) and moderate or higher transmisivity. Thus aquifer transmisivity in the cited areas are of good quality and the produce can sustain the people of the areas and neighboring environs for long period of time. I recommend that the samples of VES water locations should be tested from time to time to ascertain its Level of contaminations for future remedial measure and a water system for the general public should be drilled in the aforementioned VES points.