Stages Of Spreading Research Articles

Three stages of Marangoni-driven film spreading for miscible fluids

The Marangoni-driven film spreading in the fully miscible droplet–reservoir system was experimentally studied. Three stages of film spreading were identified over a relatively long time, with the power-law exponent n (R ∼ tn, R is film radius, t is time) nonmonotonically transitioning from 3/4, to 1/4, and back to 3/4. The variation of the Marangoni stress was found to be responsible for the three-stage power-law relationships, with the tangential stretching effect of the expanding liquid–air interface governing stages I and III and the normal diffusion effect dominating stage II. This work presents a unified interpretation of the inconsistent power-law relationships reported from previous studies on Marangoni-driven film spreading for miscible fluids.

교수자·학습자 요구분석에 기반한 코로나19 확산단계별 대학의 원격수업 유형과 운영방안 탐색

This study tried to explore the types of distance instruction and operation plans based on the experiences and demands of instructors and learners about distance instruction that were attempted in the disaster situation of COVID-19. Therefore, this study divided the COVID-19 response situation into three stages and analyzed the experiences and needs of instructors and learners. To conduct this study, 165 instructors and 986 learners responded to the survey, and 3 instructors and 3 learners participated in the interview. As a result of the study, in the satisfaction of distance instruction in response to COVID-19, the satisfaction of instructors and learners was found to be statistically significantly different in 'understanding of learning content', 'reduction in learning volume', 'repetitive learning', and 'improvement of self-directed learning competency'. appear. In the video content utilization class, instructors responded that ‘lecture + quiz/learning activity assignments are provided’, but learners tended to perceive it as ‘lecture-type class’. Also, according to the subject type (theory/experimental practice/integration), lecture-centered classes were commonly presented as the teaching methods expected by instructors and learners in real-time ZOOM classes. In addition, a result of the survey and interview analysis of instructors and learners, six types of distance instruction were derived for each stage of COVID-19 spread. Expert validation was conducted twice for the result of deriving the distance instruction type, and the final distance instruction type and operation plan were presented. In short, this study suggests that there is a need to convert the existing face-to-face class method to a new distance instructional system from the demands of instructors and learners for distance instruction using non-face-to-face methods.

Pyroconvection Classification Based on Atmospheric Vertical Profiling Correlation With Extreme Fire Spread Observations

AbstractPyrocumulus (pyroCu) formation during convective fire‐atmosphere interaction is a driving factor causing extreme and unpredictable wildfires. Here, by investigating several cases of pyroCu occurrence, we have monitored fire‐induced changes in atmospheric boundary layer (ABL) vertical profiles of state variables (temperature, humidity, and wind). Particular emphasis is placed in relating them to observed versus modeled fire spread biases. To this end, during the 2021 fire season in the Iberian Peninsula, we conducted a pyroconvection monitoring campaign. We gathered data on hourly fire spread, plume surface, deepening and penetration stages, and in‐situ radiosoundings within wildfire plumes. European Centre for Medium‐Range Weather Forecasts ERA5 weather data completed the analysis as reference modeling information to characterize the meso and synoptic scales on the thermodynamic profiles. We propose a novel classification of pyroconvection‐type events based on (a) differences in ABL thermodynamic stability, (b) regions characterized by high turbulence in the sub or pyroCu‐layers, and (c) the reinforced entrainment of free‐tropospheric air on top of every convective plume. This classification defines four types: (a) convective plumes, (b) overshooting pyroCu, (c) resilient pyroCu, and (d) deep pyroCu/pyroCb. Those prototypes change ABL conditions (temperature, humidity, height) differently depending on the dry or moist convection enhancement that drives them. Using this distinct behavior, we find correlations between observed ABL thermodynamic changes after fire‐atmosphere interaction and fire spread biases. Our findings pave the way to quantify the pyroconvection effect on fire spread and facilitate safer and more physically sound decisions when analyzing extreme fires.

Relics of ophiolite-bearing accretionary wedges in NE Brazil and NW Africa: Connecting threads of western Gondwana´s ocean during Neoproterozoic times

Neoproterozoic breakup of Rodinia resulted in the formation of several oceanic realms between dispersing cratons, which were later consumed during the assembly of Gondwana. In its western portion, the interior orogenic belts of Gondwana formed during the Brasiliano-Pan African Orogeny in the late Neoproterozoic-early Cambrian. Available geophysical, structural and petrological data suggest that the complex network of shear zones that once connected the Borborema province (NE Brazil), Tuareg shield (Hoggar) and Central African domain (NW Africa) likely represent ancient sutures that mark collisional episodes between Archean-Paleoproterozoic paleocontinents such as Amazonian-West African and São Francisco-Congo. Mafic, ultramafic and sedimentary sequences associated with this set of structures respresent dismembered ophiolite slices interpreted as oceanic remnants (sensu lato) that were emplaced during the late stages of the Gondwana assembly. For instance, the composite Transbrasiliano-Khandi-In-Tedeini-Silet shear system crosscuts rock assemblages preserving a complex history of oceanic-crust-transition development (Novo Oriente complex) in association with primitive to evolved magmatic arcs and UHP rocks both in the Borborema province and NW Africa. In the central Borborema province, preserved ophiolitic slices are strongly overprinted by ductile and brittle deformation events, but partially preserved MORB-like amphibolites are akin to subduction-related-types that crystallized in early- and late Neoproterozoic times docked via terrane accretion and dispersed by strike-slip shear zones. In the southern Borborema province, an example of a Neoproterozoic ophiolitic assemblage is the Monte Orebe complex, that encompasses T-MORB mafic rocks, ultramafic lenses, and exhalative sedimentary rocks akin to early to late stages of oceanic basin spreading, emplaced during convergent plate motions between the Pernambuco-Alagoas superterrane and the São Francisco craton. Correlative units are found in Cameroon, including the strongly hydrotermalized ultramafic rocks of the Lomié and Boumnyebel complexes, that are structurally controlled by top-to-the-south verging nappes found in the N-NW margin of the Congo craton. In all scenarios, the ophiolitic complexes are related to intra-oceanic and continental magmatic arcs as well as to geophysical signatures comparable to Phanerozoic suture zones. Although strongly dismembered, scrapped off Neoproterozoic oceanic crust partially preserved within the major belts of western Gondwana demonstrate the role of accretion-collisional orogenesis during its assembly.

Hydrodynamics and crystallization of NaCl aqueous solution droplet impact on heated surface

The characteristics of NaCl aqueous solution droplet impact on heated surfaces were captured by a high-speed camera for temperatures from 80 to 480 °C and impact velocities from 1.17 to 4.50 m/s. The NaCl crystal morphologies after the solution vaporized were used to help understand the crystallization and flow. Below the saturation temperature, the droplet experiences impact, spreading, oscillation, evaporation and evaporation coupled with crystallization. The salts gradually accumulate at the precursor line which moves toward the droplet center to finally form regular crystals from the NaCl aqueous solution. The results show that the impact velocity directly affects the crystal shell formation, while the mass concentration mainly affects the crystal distribution. Compared with pure water, the NaCl aqueous solution droplets show different boiling regimes with surface temperature since the salt crystal deposition increases the boiling and the Leidenfrost temperature. Six typical boiling regimes were identified to classify the boiling characteristics based on the surface temperature and impact velocity. A central jet was observed for surface temperatures of 280 ∼ 440 °C for an NaCl mass concentration of 0.2 due to the blocking effect from the violent boiling during the early spreading stage. The curves separating the central jetting regime and the other regimes are not linear.

3D Simulations of Freezing Characteristics of Double-Droplet Impact on Cold Surfaces with Different Wettability.

In this work, the freezing characteristics of double-droplet impact on three typical wettability surfaces were investigated by coupling the solidification and melting VOF models. Different temperature conditions were adopted to study the influence of icing speed on droplet behavior. Simulation results show that the motion of the double-droplet impact is consistent with that of a single droplet in the early spreading stage but behaves differently in the retraction stage. The wetting area evolution during the impact-freezing process shows different tendency for hydrophilic and hydrophobic surfaces: Compared with single droplets, double droplets have a smaller wetting area factor on hydrophilic surfaces but a larger one on superhydrophobic surfaces. In addition, three typical impact results are observed for the double-droplet impact on a superhydrophobic cold surface: full rebound, adhesive avulsion, and full adhesion, which reflects the interaction of droplet merging and solidification during the impact freezing of the double droplet. These findings may deepen our understanding of the mechanism of impact freezing on a cold surface, it provides reference for the associated applications and technologies in icing/anti-icing.

On axisymmetric dynamic spin coating with a single drop of ethanol

We carried out experimental and numerical investigations on the axisymmetric spreading evolution of dynamic spin coating with a single drop of ethanol. The results show that the dynamic spreading process consists of two stages: inertial spreading stage and centrifugal thinning stage. These two stages are connected by a transient state in between characterized by the minimum contact line moving velocity. The Weber number determines the spreading in the first stage, similar to the case of the impact of a drop on a static substrate. The rotational Bond number has a marginal effect on the inertia spreading and the radius at the transient state. In the centrifugal thinning stage, the rotational Bond number dominates the flow while the effect of the Weber number is negligible.

Life cycle of COVID-19 Progression in a Given Region

The study focuses on revealing the typical patterns of COVID-19 spread. The identification of regularities is based on conceptual processing data, in which a sample is approximated by model functions expressing a specific phenomenological concept of the process in question. The reconstruction of desired parameters is hindered by insufficient information on the growth features, the limited volume of the required experimental data, and incomplete elucidation of the phenomenological properties of the objects required to formulate complex models. The investigation addresses these limitations using the Verhulst equation, which expresses the general factors of object growth and adequately describes the growth dynamics in the context of significant theoretical uncertainties regarding an object under study. The need for identifiability and numerical stability of the model parameter estimates is also addressed, and a special regularization approach is applied to obtain an adequate and stable picture of the virus’s evolutionary dynamics in the context of significant uncertainties. The results demonstrate that the growth of the viral population can be integrally described by two variable parameters of the Verhulst equation. Interpreting the reconstructed functions indicates the existence of the typical pattern of seven stages of COVID-19 spread. The possibility of radically managing the number of infected persons is established. The proposed processing of coronavirus cases is of practical value for the preclinical diagnosis and control of virus spread in any geographic area, such as a district, city, local region, or country.

Early-confinement strategy to tackling COVID-19 in Morocco; a mathematical modelling study

Morocco is among the countries that started setting up confinement in the early stage of the COVID-19 spread. Comparing the number of cumulative cases in various countries, a partial lock-down has delayed the exponential outbreak of COVID-19 in Morocco. Using a compartmental model, we attempt to estimate the mean proportion of correctly confined sub-population in Morocco as well as its effect on the continuing spread of COVID-19. A fitting to Moroccan data is established. Furthermore, we have highlighted some COVID-19 epidemic scenarios that could have happened in Morocco after the deconfinement onset while considering a different combination of preventive measures.

Structure and dynamics of the Tonga subduction zone: New insight from P-wave anisotropic tomography

The Tonga-Lau-Fiji region is important to study plate-plume and subduction-ridge interactions, but its deep mantle structure is still not very clear. Here we present high-resolution tomography of 3-D P-wave azimuthal anisotropy down to 400 km depth of the Tonga subduction zone derived from arrival-time data of local earthquakes recorded at seafloor and land seismometers. The subducting Tong slab is imaged as high-velocity anomalies at depths of 100-400 km, whereas large-scale low-velocity anomalies down to 400 km depth are revealed in the mantle wedge beneath the backarc basin and volcanic arc. Trench-parallel anisotropy beneath the Lau Basin extends southwards to ∼140 km depth at ∼20.5°S, representing the extent of both southward flow of the Samoan plume and toroidal flow by the slab rollback. At depths of 140-400 km, the Lau Basin and Fiji Plateau mainly exhibit plate-parallel fast-velocity directions (FVDs) north of ∼20.5°S, indicating strong corner flow in the mantle wedge driven by the slab subduction and dehydration. The Tonga slab exhibits trench-parallel FVDs at depths of <200 km, reflecting fossil fabric formed during the plate spreading stage, whereas, at greater depths, the slab mainly exhibits trench-normal FVDs, which may reflect complicated deformations within the slab. These results suggest that the Samoan plume has a significant impact on the Tonga-Lau-Fiji region, leading to variations in the scale and depth extent of mantle flows.

A comparative study on horizontal flame spread behaviors of thermoplastic polymers with different melt flow indexes under external radiation

• Effects of thickness and external radiation on horizontal flame spread were investigated. • Relationship between flame spread rate and external radiation heat flux was obtained. • A prediction model for mass loss rate during horizontal flame spread under external radiation was developed. • Incident heat flux has a power-law relationship with dimensionless distance between flame front and sample edge. The flame spread behaviors of thermoplastic polymers are intimately related to the properties of the material itself and the external environment. In this study, three different thermoplastic polymers, polymethyl methacrylate (PMMA), polypropylene (PP) and polystyrene (PS), were used. Four different sample thicknesses (denoted by d , 1–4 mm) and five different external radiation heat fluxes ( q ″ ̇ e , 0.0–10.0 kW/m 2 , with an interval of 2.5 kW/m 2 ) were designed for the experiments. To explore the impacts of melt flow index, sample thickness and external radiation heat flux on horizontal flame spread of thermoplastic polymers, 60 experimental conditions were carried out by altering d and q ″ ̇ e . The experimental results show that the horizontal flame spread process of thermoplastic polymers presents three stages, a growth stage, a steady spread stage and a decay stage. The flame spread characteristics of thermoplastic polymers are significantly different, which are mainly reflected in the large difference in melt flow behavior. The effect of sample thickness on flame spread behavior is less evident than that of external radiation heat flux. A prediction model for the mass loss rate of thermally thin thermoplastic polymers under external radiation is established based on the heat and mass transfer analysis, which is in good agreement with the experimental results. In addition, the incident heat flux in the preheating zone has a power-law relationship with the dimensionless distance between the flame front and the sample edge on horizontal flame spread process of thermoplastic polymers. The results can provide reference for the practical application of thermoplastic polymers in building fire protection engineering.

Numerical study on the impact of wall thermal inertia on maximum smoke temperature and longitudinal attenuation in long channel fires

In order to better understand the law of smoke propagation in long channel fires and enhance the fire protection of channel structure with different lining materials, a series of fire simulations were carried out by Fire Dynamics Simulator (FDS) to investigate the impact of wall thermal inertia on the maximum smoke temperature and longitudinal attenuation under the channel ceiling. Five wall materials corresponding from the foam concrete to the steel with thermal inertia ranging from 0.1 to 165 kW2•s/(m4·K2) and four heat release rates (5 MW, 7.5 MW, 10 MW and 12.5 MW) were employed. The maximum smoke temperature above the fire source and the temperature distribution under the ceiling along the channel longitudinal centerline were attained and analyzed. The results show that the maximum smoke temperature is significantly affected by the channel wall thermal property and increases with the decrease of wall thermal inertia. Based on the simulative data, a modified model taking the influence of wall thermal inertia into consideration is put forward to predict the maximum gas temperature below the ceiling. Further, the effect of channel wall thermal inertia on the longitudinal smoke temperature decay can be negligible when the thermal inertia is greater than or equal to 1.21 kW2•s/(m4·K2), however, the foam concrete wall with the thermal inertia of 0.1 kW2•s/(m4·K2) results in a smaller attenuation rate due to less heat conducted into the channel wall. Meanwhile, the smoke temperature distribution along the channel longitudinal centerline is also related to the heat release rate (HRR), and the larger the HRR, the slower the temperature decay. The investigation indicates that the temperature distribution along the longitudinal direction follows an exponential attenuation in the near fire field but presents a form of the sum of two exponential functions in the one-dimensional smoke propagation stage. Then taking the effect of wall thermal inertia and heat release rate into account, two novel models characterizing the law of longitudinal temperature attenuation were developed near fire source and in the one-dimensional smoke spread stage respectively.

Epidemiology of human papillomavirus related cancers in India: findings from the National Cancer Registry Programme.

Human papillomavirus (HPV) causes more than one-fourth of infection related cancers globally. The present study summarises the epidemiology of HPV related cancers in India, with a special focus on cervical and oropharyngeal cancer, utilising the National Cancer Registry Programme (NCRP) data. The data on HPV related cancer incidence and treatment were extracted from 28 population-based and 96 hospital-based cancer registries under the NCRP network. Incidence was presented as rates, clinical extent of disease and treatment provided as percentages. Joinpoint regression analysis was performed to calculate annual percent change in age adjusted incidence rates (AARs) over time. Incidence of HPV related cancers for 2025 was projected. Among all cancers, 7.5% were HPV related cancers. Cervical cancer (87.6%) and oropharyngeal cancer (63.2%) were the most common HPV related cancers in India among females and males, respectively. Cervical cancer was highest in Papumpare district (AAR: 27.7 per 100,000) and oropharyngeal cancer among males in East Khasi Hills district Population Based Cancer Registry (AAR: 11.4 per 100,000). In most PBCRS, cervical cancer incidence rate decreased significantly over the period of time. The majority of these cancers presented at locoregional spread stage of the disease and were treated with chemoradiation. The projected incidence of HPV related cancers is expected to increase to 121,302 by 2025. Implementation of effective prevention and control strategies like HPV vaccination and scaling up of screening could reduce the burden of HPV related cancers. Evidence from NCRP serves as the baseline to monitor the impact of HPV related policies and programmes in improving the outcome and prognosis.

Forces governing the dynamics of liquid spreading in packed beds

Liquid spreading through a randomly packed particle-resolved bed influenced by capillary or inertial ($AB_s \sim 1$), and gravitational force (moderately ($AB_s \sim 0.1$) and strongly ($AB_s \sim 0.01$)) is investigated using the volume-of-fluid simulations. The relative contribution of governing forces at different stages of spreading is analysed using the time evolution of Weber ($We_I$) and$AB_I$numbers. We show that the dynamics of liquid spreading at$AB_s \sim 1$is primarily governed by the inertial force in the beginning ($AB_I &gt; 1$,$We_I &gt; 1$) followed by the capillary force at$t/t^* \sim 1$. This interplay of governing forces leads to inertia- and capillary-induced bubble entrapments at the void scale and promote lateral liquid spreading. When the$AB_s \sim 0.1$, the$t/t^*$for which the flow is governed by inertial ($AB_I &gt; 1$,$We_I &gt; 1$) and capillary forces ($AB_I &gt; 1$,$We_I &lt; 1$) decreases and the relative contribution of gravitational force is substantial at large$t/t^*$($AB_I &lt; 1$). This force balance leads to unified-void filling characterised by negligible bubble trapping and results in a decrease in the lateral spreading. Further decrease in the$AB_s$to${\sim } 0.01$results in liquid spreading primarily governed by gravitational force ($AB_I &lt; 1$) with small contribution of inertial and capillary forces at the very beginning leading to trickling flow and a further decrease in lateral spreading. Finally, a regime map is proposed, which provides the relationship between different forces, void-scale events, and the resultant liquid spreading at$t/t^* \sim 1$.

Dynamic simulation of droplet impacting on superhydrophobic surface with cubic protrusion

Droplet impact dynamics on a superhydrophobic surface with a cubic protrusion was simulated by the lattice Boltzmann method and the contact time reduction mechanism due to the fact that the cubic protrusion was explored. In addition, the droplet bouncing behavior was analyzed with the effect of a wide range of Weber numbers (18.28–106.77). The simulated results showed three distinct bouncing modes, which are bouncing with no ring formation, bouncing with ring formation and disappearance, and bouncing with ring formation. The contact time can be sharply reduced by up to 58.41% as the We number exceeds the critical value 67.16, which is induced by the liquid ring bouncing generated by the collision between the inner and outer rims. In addition, no effect can be seen during the spreading stage, and hence, the liquid ring punctured by the cubic protrusion mainly reduces the retraction time of the droplet impact process. Moreover, the retraction distance can be shortened with the increase in We. Symmetrical dynamics during spreading and retraction due to the cubic protrusion can be seen, which is different from the asymmetric behavior on a macroridge. Discussions on the instantaneous velocity field further support the reduction mechanism of the contact time.

On the stages of spread of traditional Chinese medicine in Russia

On the stages of spread of traditional Chinese medicine in Russia

Effect of Contact Angle Hysteresis on Evaporation Dynamics of a Sessile Drop on a Heated Surface

Contact angle hysteresis (CAH) is a significant factor affecting the drop motion on solid substrates. A model of CAH is introduced to explore the influence of CAH on the dynamics of a sessile drop on a uniformly heated surface, and a two-dimensional evolution equation of the drop thickness is established using the lubrication approximation and Navier slip boundary conditions. A numerical simulation is performed to examine the dynamic behaviors of an evaporating drop, and the drop profile, contact angle, contact line, and moving speed are investigated. Simulated results indicate that the drop evolution process involves drop spreading, pinning, and depinning of the contact line. In the drop spreading stage, when the hysteresis angle increases, the spreading period is shortened, and the spreading radius and spreading speed are reduced; in contrast, the pinning period is raised, and the mass of the drop is apparently reduced with increasing hysteresis angle. In the depinning stage, the CAH declines the contact angle, and a flatter pattern is evolved, thereby improving the heat transfer performance, promoting drop evaporation, and shortening the depinning time. The presence of CAH can speed up the drying of the drop, and the large hysteresis angle leads to faster evaporation. Regulating the CAH is an effective way to manipulate the motion of the contact line for an evaporating drop.

The role of phylogenetic relatedness on alien plant success depends on the stage of invasion.

Darwin's naturalization hypothesis predicts successful alien invaders to be distantly related to native species, whereas his pre-adaptation hypothesis predicts the opposite. It has been suggested that depending on the invasion stage (that is, introduction, naturalization and invasiveness), both hypotheses, now known as Darwin's naturalization conundrum, could hold true. We tested this by analysing whether the likelihood of introduction for cultivation, as well as the subsequent stages of naturalization and spread (that is, becoming invasive) of species alien to Southern Africa are correlated with their phylogenetic distance to the native flora of this region. Although species are more likely to be introduced for cultivation if they are distantly related to the native flora, the probability of subsequent naturalization was higher for species closely related to the native flora. Furthermore, the probability of becoming invasive was higher for naturalized species distantly related to the native flora. These results were consistent across three different metrics of phylogenetic distance. Our study reveals that the relationship between phylogenetic distance to the native flora and the success of an alien species changes from one invasion stage to the other.

Adsorption process and mechanisms of AEO-3/dodecane mixed collector on low-rank coal surface driven by water flow: A non-equilibrium molecular dynamics simulation study

During coal slime flotation, the collector is adsorbed to the coal in the form of fine oil droplets in the turbulent slurry. And understanding the adsorption behavior of collector oil droplets on the coal surface is important for the development of efficient collector. In this study, the adsorption process and mechanism of triethylene glycol dodecyl ether (AEO-311triethylene glycol dodecyl ether.)/dodecane mixed collector oil droplet (MCOD22mixed collector oil droplet.) on the surface of low-rank coal driven by water flow were investigated by non-equilibrium molecular dynamics simulations. The changes of the mass center velocity of MCOD, contact area and interaction energy between MCOD and coal during the simulation were analyzed, and the adsorption process was divided into the adhesion stage, spreading stage and equilibrium stage. The kinetic reason for the adsorption of AEO-3 molecules at the interface was found. The pushing of oil droplet by the water flow caused the AEO-3 molecules to be slowly pressed into the contact interface between the oil droplet and coal, and the adsorption occurred. The presence of polar oxygen-containing functional groups on the AEO-3 molecule makes it much more strongly adsorbed on low-rank coal than dodecane. Water molecules play an important role in the adsorption process of AEO-3 with coal, and the bridging action of water molecules that enables indirect adsorption of collector with coal was proposed. The water molecule connects AEO-3 and coal molecules, which cannot form hydrogen bond due to the distance, through hydrogen bonding, and inserts between alcohol oxygen, ether oxygen and carbonyl oxygen, which are originally mutually exclusive, so that the three of them (OAEO-3, H2O and Ocoal) are connected together through hydrogen bonding (OAEO-3…H-O-H…Ocoal), and the stability of AEO-3 adsorption on coal surface is greatly enhanced. The presence of strong indirect electrostatic interactions between polar collector and coal generated by the bridging action of water molecules proves that it is the strong electrostatic interactions that are the reason for the strong flotation performance of polar collector on low-rank/oxidized coals.

Comparative Study on the Spreading Behavior of Oil Droplets over Teflon Substrates in Different Media Environments.

This paper comparatively investigated the spreading process of an oil droplet on the surface of highly hydrophobic solid (Teflon) in air and water media using a high-speed imaging technology, and analyzed their differences in spreading behavior from the perspective of empirical relations and energy conservation. Furthermore, the classical HD and MKT wetting models were applied to describe the oil droplet spreading dynamics to reveal the spreading mechanism of oil droplets on the Teflon in different media environments. Results showed that the entire spreading process of oil droplets on Teflon in air could be separated into three stages: the early linear fast spreading stage following , the intermediate exponential slow spreading stage obeying , and the late spreading stage described by . However, the dynamics behavior of dynamic contact angle during the oil droplet spreading on Teflon in water could be well described by these expressions, and . Clearly, a significant difference in the oil droplet spreading behavior in air and water media was found, and the absence of the intermediate exponential spreading stage in the oil–water–Teflon system could be attributed to the difference in the dissipated energy of the system because the dissipation energy in the oil–water–solid system included not only the viscous dissipation energy of the boundary layer of oil droplet, but also that of the surrounding water which was not included in the dissipation energy of the oil–air–solid system. Moreover, the quantitative analysis of wetting models suggested that the MKT model could reasonably describe the late spreading dynamics of oil droplets (low TPCL velocities), while the HD model may be more suitable for describing the oil droplet spreading dynamics at the early and intermediate spreading stages (high TPCL velocities).