Dimensionless Number

One essential forensic technique for reconstructing the events of violent crimes involving bloodshed is bloodstain pattern analysis (BPA). The shape and diameter of blood droplets from four common species—humans (Homo sapiens sapiens), pigs (Sus scrofa domestica), goats (Capra ibex), and chickens (Gallus gallus)—are analysed in this study to investigate inter-species differences in bloodstain patterns. Blood samples were dropped onto twelve distinct horizontal surfaces, including cardboard, glass, metal, cotton fabric, and tile, from a fixed height of 14 inches. The findings advance our knowledge of BPA in forensic investigations by demonstrating how stain morphology is influenced by surface texture and species-specific blood characteristics. In addition to offering useful reference data for differentiating between human and animal blood in forensic casework, these discoveries improve the accuracy of crime scene reconstructions.

: In the last years, the availability of testing facilities of large capabilities, able to perform testing programs of full scale devices under realistic loading conditions, improved the familiarity with the behaviour of isolators as curved surface sliding bearings. Although the tribological properties of the sliding interfaces are of major importance for the proper response of sliding devices, a relatively limited number studies is available on the behaviour of engineering plastics investigating the influence of pressure and sliding velocity replicating service parameters typical of seismic devices. The present paper illustrates the experimental campaign carried out at the Bearing Tester System of the EUCENTRE TREES Lab of Pavia (Italy), on 2 full scale devices equipped with a newly developed material. A proper experimental protocol has been defined, with the objective of characterizing all the response quantities of interest, with a focus on the dependence of the frictional proper...

A wide test campaign has been carried out at the EUCENTRE TREES Lab of Pavia (Italy), on almost 400 Curved Surface Sliders (CSS) of two different typologies, designed to feature the same structural response from the performance point of view. Test campaigns of comparable size are not currently documented or public, to the authors' knowledge. Results of the test campaign proved to be interesting on a twofold point of view, within the perspective of the testing prescriptions imposed by the most recent codes on seismic isolation devices. As far as the stability and repeatability of results is concerned, the significantly large sample of tested devices allows realizing the dispersion of the relevant response quantities. Such an information can be important to calibrate the expected range of variation of the isolator properties, since generally only a reduced sample of isolators is tested for ordinary projects, both for type and quality control tests. Moreover, it has to be observed ...

O conhecimento dos valores das pressões e flutuação de pressões no interior do ressalto hidráulico é de interesse para o projeto e dimensionamento de bacias de dissipação. A utilização de modelos reduzidos auxilia no de projeto dessas estruturas hidráulicas. Este trabalho faz parte de uma pesquisa que vem sendo realizada no campo da análise da macroturbulência em estruturas de dissipação de energia por ressalto hidráulico e tem como objetivo a análise e comparação das pressões em ressalto hidráulico afogado em protótipo e em modelo reduzido para a UHE Porto Colômbia. Nas medições no protótipo, realizadas em 1996 por iniciativa de Furnas Centrais Hidrelétricas S.A., foram coletadas amostras com número de Froude entre 3, 8 e 8, 1. Nas medições no modelo reduzido na escala 1:100, realizadas em 2001 no Laboratório de Hidráulica Experimental de Furnas (LAHE), foram coletadas com números de Froude entre 3, 2 e 6, 7. Neste trabalho serão apresentados a distribuição longitudinal de pressão média, desvio padrão da amostra, coeficiente de assimetria e coeficiente de curtose, adimensionalisados em relação aos parâmetros hidráulicos do escoamento. (FAPERGS/IC).

Apresenta-se uma revisão da literatura sobre os escoamentos em quedas sucessivas, assim como a respeito de escoamentos sobre um degrau. Foram analisadas metodologias para a previsão do alcance do jato, alturas características dos escoamentos, energia dissipada e eficiência de reoxigenação. As equações foram comparadas entre si e com dados experimentais, fornecendo informações sobre desvios, concordâncias, divergências e lacunas de conhecimento devido à falta de dados. Concluiu-se não haver concordância entre as metodologias para o cálculo da energia dissipada por um degrau e para o alcance do jato. Para mais de um degrau, não há consenso sobre a previsão da ocorrência do regime estudado e seus sub-regimes. Há lacunas sobre o cálculo da energia dissipada e poucos estudos sobre a reaeração. Tais lacunas e potenciais avanços sobre o tema conduziram, no presente trabalho, à proposição de uma equação para a energia dissipada e uma equação para o cálculo da eficiência da reaeração.

We report on direct measurements of the basal force components for granular material flowing down a smooth incline. We investigate granular flows for a large range of inclination angles from 13.4° to 83.6° and various gate opening of the chute. We find that the effective basal friction coefficient, µB, obtained from the ratio of the longitudinal force to the normal one exhibits a systematic increase with increasing slope angle and a significant weakening with increasing particle hold-up H (the depth-integrated particle volume fraction). At low angles, the basal friction is slightly less than or equal to tanThe deviation from tancan be interpreted as a contribution from the side-wall to the overall friction. At larger angles, the basal friction µB saturates at an asymptotic value that is dependent on the gate opening of the chute. Importantly, our data confirm the outcomes of recent discrete numerical simulations. First, for steady and fully developed flows as well as for moderately accelerated ones, the variation of the basal friction can be captured through a unique dimensionless number, the Froude number Fr, defined as Fr=𝑈 ̅ /(gHcos) 1/2 , where 𝑈 ̅ is the mean flow velocity. Second, the mean velocity scales with the particle hold-up H with a power exponent close to 1/4, contrasting with the Bagnold scaling (𝑈 ̅ ~H3/2 ).

Estudos voltados à compreensão da hidrodinâmica de vertedouros em degraus têm sido desenvolvidos em diversas instituições ao longo de mais de duas décadas, constituindo, ainda hoje, um campo de pesquisas relativamente amplo em decorrência da complexidade imposta pela presença dos degraus. Apesar das dificuldades encontradas na quantificação das numerosas variáveis relacionadas ao escoamento em tais estruturas hidráulicas, é possível encontrar na literatura metodologias coerentes e consistentes, amparadas por criteriosos estudos experimentais e numéricos que dão ao engenheiro subsídios para a elaboração de projetos. O presente trabalho reúne resultados de diferentes pesquisadores por meio de comparações de algumas grandezas hidráulicas envolvidas no fenômeno, dentre as quais se destaca o comprimento do ressalto na bacia de dissipação, através do qual é proposta uma metodologia simplificada para a estimativa do mesmo.

A general seismic event can be considered as the superposition of two individual time histories of ground acceleration, acting simultaneously at the base of a structural system, along the main directions of a given reference system. Response spectra can be computed either for each component, or for the global seismic event, by considering a Single Degree of Freedom with different values of self-period, subjected to both the x and y accelerograms. Such a bi-directional response spectrum has higher spectral coordinates with respect to the individual ones, because of the instantaneous contributions of both directions of ground motion in the structural response. Nonetheless, an earthquake is expected to release most of the total energy of the event along an actual radial direction, mainly due to the propagation direction of seismic waves from the hypocenter toward the ground surface, even though the ground motion develops according to a random trajectory. A recent research work proposed an analytical procedure for the computation of an "equivalent uniaxial accelerogram" for a bidirectional earthquake: the proposed theory allows to compute a single ground acceleration time-history, related to a proper direction angle, able to reproduce the same effects of a two-components seismic event on a base-isolated structural system: results showed a good agreement between the equivalent radial and the bidirectional structural responses, even if non-negligible differences were observed. In this work a more refined procedure is proposed for the definition of the equivalent unidirectional accelerogram for a base-isolated structure. A wide validation study is reported, by analyzing 100 bidirectional seismic events: two different ranges for vibration period have been assumed, in order to evaluate the accuracy of the overall procedure, by considering a large rather than a small portion of the reference response spectrum. Finally, a case study structure has been modeled, to underline effects of the equivalent radial response, in comparison to the reference bidirectional case.

Matrix-to-fracture transfer functions assume that fractures are instantaneously filled with water, leading to constant, time-independent shape factors. However, the water filling fracture regime, which can be observed for some conditions such as small injection rates, does not lead to constant shape-factors and is difficult to solve using commercial flow simulators. The purpose of this study is to (1) show the impact of rock wettability in reservoir simulation and upscaling procedures, and, (2) apply an upscaling matching procedure based on time-dependent matrix-fracture fluid transfer term. This work shows that the increase of rock preference for water can lead to upscaling limitations due to the partially immersed fractures behavior observed in cases with small fracture apertures and small injection rates, for waterwet rocks. A time-dependent matrix-fracture fluid transfer term was proposed for upscaling matching procedures. The developed method solves the limitation of time-independent shape factors and allows the dual porosity flow model to properly represent the dynamic behavior for different wettability scenarios. This work aims to contribute for understanding the impact of rock wettability in upscaling and reservoir simulation of fractured reservoirs and, provides solutions for flow simulation of dual porosity flow models under a water filling-fracture regime, which is common in water-wet rocks.

Seismic reliability of steel structures isolated using the frictional pendulum system bearings and subjected to artificial earthquake ground motions is studied herein. The superstructure is idealised as a linear shear-type flexible building as well as the FPS devices are described by adopting a widespread model which considers the variation of the friction coefficient with the velocity. The uncertainty affecting both the seismic inputs, modelled as non stationary random processes within the power spectral density method, and the friction coefficient at large velocity is considered through appropriate probability density functions. Incremental dynamic analyses are developed in order to evaluate the fragility curves related to both superstructure and isolation level. Finally, considering the seismic hazard curve related to a site near Sant'Angelo dei Lombardi (Italy), the seismic reliability of the overall steel system is evaluated.

Chemical compositional simulation of enhanced oil recovery and surfactant enhanced aquifer remediation processes is a complex task that involves solving dozens of equations for all grid blocks representing a reservoir. In the present work, we perform a numerical validation of the newly developed mathematical formulation which satises the conservation laws of mass and energy and allows applying a sequential solution approach to solve the governing equations separately and implicitly. Through its application to the numerical experiment using a wettability alteration model and comparisons with existing chemical compositional model's numerical results, the new model has proven to be practical, reliable and stable.

The re-centring capability is recognized as a fundamental function of any effective isolation system, not only because it is associated to small or negligible deformation at the end of the earthquake but rather because it prevents displacement build up that may limit the capability of the structure to withstand aftershocks and future earthquakes. The current Eurocode recommends to estimate the maximum total

This comparative review highlights the relationships between the disciplines of bloodstain pattern analysis (BPA) in forensics and that of fluid dynamics (FD) in the physical sciences. In both the BPA and FD communities, scientists study the motion and phase change of a liquid in contact with air, or with other liquids or solids. Five aspects of BPA related to FD are discussed: the physical forces driving the motion of blood as a fluid; the generation of the drops; their flight in the air; their impact on solid or liquid surfaces; and the production of stains. For each of these topics, the relevant literature from the BPA community and from the FD community is reviewed. Comments are provided on opportunities for joint BPA and FD research, and on the development of novel FD-based tools and methods for BPA. Also, the use of dimensionless numbers is proposed to inform BPA analyses.

Experimental studies performed on friction-based isolators have shown widely sparse frictional response, as direct effect of intrinsic properties of the devices and the vertical load variation. Moreover, in practical applications mounting laying defects consisting of uneven inclinations of the sliding surfaces with respect to the horizontal plane have been recognized as potential cause of deviation from the response assumed in the design phase. In this paper mono and bi-axial motions of a base-isolated RC building have been investigated; the aim of the work is to identify the effects of both laying defects and friction variation on the seismic response.

: In the last years, the availability of testing facilities of large capabilities, able to perform testing programs of full scale devices under realistic loading conditions, improved the familiarity with the behaviour of isolators as curved surface sliding bearings. Although the tribological properties of the sliding interfaces are of major importance for the proper response of sliding devices, a relatively limited number studies is available on the behaviour of engineering plastics investigating the influence of pressure and sliding velocity replicating service parameters typical of seismic devices. The present paper illustrates the experimental campaign carried out at the Bearing Tester System of the EUCENTRE TREES Lab of Pavia (Italy), on 2 full scale devices equipped with a newly developed material. A proper experimental protocol has been defined, with the objective of characterizing all the response quantities of interest, with a focus on the dependence of the frictional proper...

Nowadays, the use of seismic isolation within the Italian and European context is gaining more and more acknowledgement, thanks to the high level of protection which can be guaranteed to a structure from the earthquake damage. However, the installation of devices within complex structural systems may influence the actual response due to the random variation of the installation and operating conditions with respect to the theoretical structural scheme. It is then of paramount importance a proper assessment of the overall isolating system response, considering the variability of the construction conditions.

We demonstrate how geological heterogeneity impacts the effectiveness of surfactant-based enhanced oil recovery (EOR) at larger (inter-well and sector) scales when upscaling small (core) scale heterogeneity and physicochemical processes. We used two experimental datasets of surfactant-based EOR where spontaneous imbibition and viscous displacement, respectively dominate recovery. We built 3D core-scale simulation models to match the data and parameterize surfactant models. The results were deployed in high-resolution models that preserve the complexity and heterogeneity of carbonate formations in the inter-well and sector scale. These larger-scale models were based on two outcrop analogues from France and Morroco, respectively, which capture the reservoir architectures inherent to the productive carbonate reservoir systems in the Middle East. We then assessed and quantified the error in production forecast that arises due to upscaling, upgridding, and simplification of geological heterogeneity. Simulation results showed a broad range of recovery predictions. The variability arises from the choice of surfactant model parameterization (i.e., spontaneous imbibition vs viscous displacement) and the way the heterogeneity in the inter-well and sector models was upscaled and simplified. We found that the parameterization of surfactant models has a significant impact on recovery predictions. Oil recovery at the larger scale was observed to be higher when using the parametrization derived from viscous displacement experiments compared to parameterization from spontaneous imbibition experiments. This observation clearly demonstrated how core-scale processes impact recovery predictions at the larger scales. Also, the variability in recovery prediction due to the choice of surfactant model was as large as the variability arising from upscaling and upgridding. Upscaled and upgridded models overestimated recovery because of the simplified geology. Grid coarsening exacerbated this effect because of the increased numerical dispersion. These results emphasize the need to use correctly configured surfactant models, appropriate grid resolution that minimizes numerical dispersion, and properly upscaled reservoir models to accurately forecast surfactant floods. Our findings present new insights into how the uncertainty in production forecasts during surfactant flooding depends on the way surfactant models are parameterized, how the reservoir geology is upscaled, and how numerical dispersion is impacted by grid coarsening.

Seismic isolation systems provide a significant reduction of the structural vulnerability of both buildings and bridges subjected to earthquake excitations. The implemented devices provide a low value of global lateral stiffness, which leads to the proper period elongation and, consequently, the reduction of inertia forces at all levels is ensured. On the other hand, high displacement demands can be achieved at the isolation layer: such a displacement value can be reduced, by increasing the dissipative capacity of the implemented devices. Nowadays a number of technical solutions are used in the common practice: among the others, Concave Surface Slider devices and Rubber Bearings with & without lead core are generally adopted. In the design phase the main characteristics of isolation devices are computed, according to simplified procedures, which consider the mean values of mechanical properties as deterministic parameters, even though research and commercial experimental campaigns h...

Structural vulnerability of buildings can be significantly reduced if seismic isolation systems are implemented at the base of the overall system. Thanks to the low stiffness characteristics, reduced forces are experienced during a seismic event, whereas displacements are limited by the provided energy dissipation of the installed devices. In the design phase, for the assessment of the response of a considered structure, deterministic mechanical parameters are generally assumed, which correspond to the mean values of the real experimental response. On the other hand, outcomes of several testing campaigns have revealed non negligible variability of the main response characteristics of isolators, which may lead to unexpected behaviors of the isolated structure. In the present endeavor a parametric study has been performed, in order to evaluate the consequences of the variability of the main mechanical characteristics of the implemented devices on the response of a base-isolated structure. Concave Surface Slider devices have been considered: results have led to preliminary guidelines for the correct assumptions in the design phase of isolation devices in real applications.

Sliding bearings have been extensively used to implement base isolation design in civil engineering works. Testing of isolators is conducted for characterizing the design properties to be used in structural analysis, as well as for verifying the performance of the devices before their application. The quantification of the effects of scaling specimens and testing on the observed coefficient of friction is an issue, due to the nonlinear dependence of the latter on several factors like load, velocity and temperature. An effort to quantify such effects is pursued in the study. The coefficient of friction is parameterized as a function of few dimensionless quantities related to heating of the sliding surfaces, and similarity conditions are assessed under which the influence of scaling is below normal production variability.

Experimental studies performed on friction-based isolators have shown widely sparse frictional response, as direct effect of intrinsic properties of the devices and the vertical load variation. Moreover, in practical applications mounting laying defects consisting of uneven inclinations of the sliding surfaces with respect to the horizontal plane have been recognized as potential cause of deviation from the response assumed in the design phase. In this paper mono and bi-axial motions of a base-isolated RC building have been investigated; the aim of the work is to identify the effects of both laying defects and friction variation on the seismic response.

Nowadays, the use of seismic isolation within the Italian and European context is gaining more and more acknowledgement, thanks to the high level of protection which can be guaranteed to a structure from the earthquake damage. However, the installation of devices within complex structural systems may influence the actual response due to the random variation of the installation and operating conditions with respect to the theoretical structural scheme. It is then of paramount importance a proper assessment of the overall isolating system response, considering the variability of the construction conditions.

In oil reservoirs about 40% of the original oil in place is produced and the rest remains as residual oil after primary and secondary oil recovery due to geological and physical factors. Additional oil can be mobilized by applying some improved oil recovery methods. However, there is no universal IOR method to be implemented in any reservoir. Efforts are made to develop IOR methods with lower risk. One of these methods is the application of sound/ultrasound waves in the reservoirs to overcome the interfacial tension between oil and water, and reduce capillary pressure in the pores. In this study, laboratory experiments on core samples were conducted to investigate the ability of ultrasound waves to mobilize additional oil. The core flooding was performed horizontally and vertically and the wave stimulation was applied at original oil in place and at residual oil saturation after performing initial waterflooding. Oil/water relative permeability was calculated to evaluate the flooding performance in the presence and the absence of wave stimulation and the rate of oil recovery was determined. In addition, water fractional flow curves were considered to determine the average water saturation after breakthrough in the presence and the absence of ultrasound waves. Moreover, the effect of wave stimulation on unconsolidated core samples was investigated. Results show that the rate of oil displacement increases due to various identified mechanisms, and the interaction of the generated waves with the fluids in porous media causes changes in relative permeability and in water breakthrough. Wave stimulation at residual oil saturation was more effective than the case of original oil in place. Therefore, this method is advised to be used in depleted reservoirs. Moreover, wave stimulation on core sample with a compressive strength of <150 psi (unconsolidated) is not recommended due to sand production.

The purpose of this research was to study forward-spatter misting patterns by shooting a firearm through a chamber of blood encased in ballistic gel to determine if there is a relationship between bloodstain pattern size as a function of distance and orientation. There is a lack of research on forward spatter, blood travelling in the direction of a bullet, as most studies focus on back spatter, blood travelling in the opposite direction of a bullet. A bullet was fired through ballistic gel containing a blood chamber, depositing bloodstains onto a large sheet of butcher paper as the target surface. In total, there were 34 trials. The distances observed were 10, 20, 40, and 80 cm, the angles tested were 30°, 60°, and 90°. The orientation between the ballistic gel and paper target varied. A criterion was established to observe the overall area and symmetry of the bloodstain patterns. Statistical analyses indicated a negative linear relation relationship between the bloodstain pattern s...

Enhanced oil recovery is a very important activity in the production of oil from reservoirs which have reached residual oil and are in need of secondary recovery methods to extract the hydrocarbons. These reservoirs to be produced require water flooding or gas injection to assist in its production. This project looks at reservoirs that are oil wet and there for when water is injected into the reservoir, which can be recovered by the use of solvent or surfactants also known as surface active agents to alter the wettability of the rocks and allow for the process of imbibition to occur and for the oil in the reservoir to be produced. There is a lot of research in the industry about the selection and optimization of surfactants but there is still a gap to cover more areas about this topic. Therefore, it is important to do more research to add to what is known about the use of surfactants in EOR applications. This project studies suitable surfactants to alter wettability, and optimize th...

This thesis presents a comprehensive simulation study on the impact of natural fractures on the performance of surfactant polymer flood in a field scale surfactantpolymer flood. The simulation model utilized for the study is a dual porosity dual permeability model representing 1/8 of a 20-acre 5-spot pattern. The model parameters studied include wettability alteration, IFT changes and mobility reduction effect. The results of this study clearly indicate the importance of reservoir description and fracture modeling for a successful surfactant-polymer flood. Naturally fractured carbonate reservoirs are usually characterized by mixed wettablility and low matrix permeability which leads to low oil recovery and high remaining oil saturation. Enhanced oil recovery methods such as surfactant-polymer flood (SPF) enhance the recovery by increasing the spontaneous imbibitions either by lowering the interfacial tension or altering the wettability. However, one of the main reasons for failed surfactant-polymer floods is under-estimating the importance of the reservoir especially the description of natural fractures and their effect on recovery.

Impact patterns that are generated on dark surfaces can become camouflaged creating difficulties with conventional photographic methods that are used when estimating the area of origin. Chemical enhancement is an alternative technique that can be used to visualize these latent bloodstains. The application of Acid Yellow 7 to already fixed bloodstains provides a robust enhancement protocol which yields minimal stain distortion. Image J software was utilized to count stains, resulting in an approximate 5% increase in small stain detection post-enhancement. Area analyses also performed with Image J demonstrates that the average area of a single stain increases by a factor of approximately 1.24 post-enhancement. When using the BackTrack ™ suite of programs this enlargement does not significantly affect the calculated impact angle of an enhanced bloodstain when compared to that of its original deposition (P= 0.585). As a result, the area of origin can be estimated within the accepted error of ± 7 cm from the known blood source. Résumé Les modèles d'impact qui sont produits sur les surfaces sombres peuvent devenir camouflé créant des difficultés avec les méthodes photographiques conventionnelles qui sont utilisés en estimant la zone d'origine. L'amélioration chimique est une technique alternative qui peut être utilisée pour visualiser ces taches de sang latentes. L'application d'Acide Jaune 7 aux taches de sang déjà fixes fournissent un protocole robuste qui produit la déformation de tache minimale. Le logiciel Image J a été utililzé pour compter des taches, résultant en une augmentation d'environ 5% dans la detection de petites taches de poste-amélioration. Les analyses de zone aussi exécuté avec l'Image J démontre que le secteur moyen d'une seule tache augmente d'un facteur d'environ 1,24 posteamélioration. Lors de l'utilisation de la suite des programmes de BackTrack ™ cet élargissement n'affecte pas significativement l'angle d'impact calculé d'une tache de sang améliorée quand comparé à cela de sa déposition originale (P = 0,585). Par conséquence, la zone d'origine peut être estimée dans l'erreur acceptée de 7 centrimètres ± de la source de sang connue.

Dynamic similarity is a widely used concept in the fluid mechanics field, and consists in placing two different-sized systems in equivalent experimental conditions. This enables removal of the effects of size and prediction of the behavior of a full size system from a scale model. The aim of this study was to test whether the Froude number (Nfr) or the Strouhal number (Str) could be used as a criterion for dynamic similarity during running. Fifteen male subjects ran barefoot on a runway in three experimental conditions (i) all subjects ran at the same speed V ¼ 3.5 m s À1 ; (ii) the speed was determined from Nfr; (iii) the stride frequency was determined from Str. Antero-posterior (Fy) and vertical (Fz) ground reaction force components were assessed. The similarity between the subjects was analysed from scale factor sets computed from anthropometric and kinetic data. The use of Str implied strong inter-subject similarity for temporal parameters (mean r ¼ 0.96, time to Fz peak, time to Fy braking peak, Fy zero fore-aft shear, time to Fy propulsive peak) while Nfr induced fewer and lower similarities (mean r ¼ 0.75, Fy zero fore-aft shear, time to Fy propulsive peak, Fy braking impulse) that only concerned antero-posterior parameters. This study brought experimental evidence that neither Nfr nor Str were sufficient for dynamic similarity during running, but that each of them made its own contribution. These findings suggested that the concomitant use of Nfr and Str should be assessed to induce inter-subject dynamic similarity during running.

This comparative review highlights the relationships between the disciplines of bloodstain pattern analysis (BPA) in forensics and that of fluid dynamics (FD) in the physical sciences. In both the BPA and FD communities, scientists study the motion and phase change of a liquid in contact with air, or with other liquids or solids. Five aspects of BPA related to FD are discussed: the physical forces driving the motion of blood as a fluid; the generation of the drops; their flight in the air; their impact on solid or liquid surfaces; and the production of stains. For each of these topics, the relevant literature from the BPA community and from the FD community is reviewed. Comments are provided on opportunities for joint BPA and FD research, and on the development of novel FD-based tools and methods for BPA. Also, the use of dimensionless numbers is proposed to inform BPA analyses.

The stability of liquid jet of dichloromethane in dense carbon dioxide was investigated in an aerosol solvent extraction system (ASES). The stability experiments were carried out at pressures ranging 30-150 bar and a temperature of 308 K, with a nozzle size diameter of 0.254 mm. Interfacial tensions of dichloromethane-carbon dioxide system were measured using a capillary rise method to correlate the stability of liquid jets with a dimensionless number. A new dimensionless number, Z*, was proposed to define an atomization flow regime of the liquid jets in dense carbon dioxide.

Most carbonate reservoirs are heterogeneous in terms of pore distribution and the matrix is extremely low permeable, hindering the flow of oil, while highly permeable fractures are the primary flow conduit. This study presents the hybrid discrete fracture network (DFN) approach to represent fracture network, more realistically, which is a continuum approach equipped with local grid refinement (LGR). The LGR is adapted at the cells that fractures are passing through, in order to describe the fracture width less than 0.1 ft. In this approach, control volume of the well lying on the fracture is extremely small and thus, in this study, four-leg horizontal well concept substitutes the vertical well with the use of equivalent well radius for overcoming the numerical convergence problem. The hybrid DFN approach was applied for CO 2-foam injection in fractured carbonate reservoirs to investigate the effect of conformance control. This foam injecting method yields more imbibition of CO 2-foam into low permeable matrix, which contains most of the oil. From the numerical results, it shows that the foam controls CO 2 velocity and this increases the contact time between CO 2 and the rock matrix since CO 2 mobility is controlled by foam, that decreases relative permeability of CO 2 and increases its viscosity.

The stability of liquid jet of dichloromethane in dense carbon dioxide was investigated in an aerosol solvent extraction system (ASES). The stability experiments were carried out at pressures ranging 30-150 bar and a temperature of 308 K, with a nozzle size diameter of 0.254 mm. Interfacial tensions of dichloromethane-carbon dioxide system were measured using a capillary rise method to correlate the stability of liquid jets with a dimensionless number. A new dimensionless number, Z*, was proposed to define an atomization flow regime of the liquid jets in dense carbon dioxide.

Oil recovery from fractured carbonate reservoirs by water flooding is often inefficient due to the commonly oil-wet nature of these rocks and the lack of sufficient spontaneous capillary imbibition driving force to push oil out from the matrix to the fracture network. Chemical processes such as surfactant/alkali-induced wettability alteration and interfacial tension (IFT) reduction have shown great potential to reduce the residual oil saturation in matrix blocks, leading to significant incremental oil recovery (IOR). However, the time required to achieve a significant amount of oil recovery is the most crucial deciding factor in field projects. The magnitude of recovery and response time of any chemical process depends on the degree of wettability alteration and IFT reduction, the nature and density of fracture network, and the matrix block size.

Traditionally, carbon dioxide (CO 2 ) injection has been considered an inefficient method for enhancing oil recovery from naturally fractured reservoirs. Obviously, it would be useful to experimentally investigate the efficiency of waterflooding naturally fractured reservoirs followed by carbon dioxide (CO 2 ) injection. This issue was investigated by performing water imbibition followed by CO 2 gravity drainage experiments on artificially fractured cores at reservoir conditions. The experiments were designed to illustrate the actual process of waterflooding and CO 2 gravity drainage in a naturally fractured reservoir in the Brass Area, Bayelsa. The results demonstrate that CO 2 gravity drainage could significantly increase oil recovery after a waterflood. During the experiments, the effects of different parameters such as permeability, initial water saturation and injection scheme was also examined. It was found that the efficiency of the CO 2 gravity drainage decrease as the rock permeability decreases and the initial water saturation increases. Cyclic CO 2 injection helped to improve oil recovery during the CO 2 gravity drainage process which alters the water imbibition. Oil samples produced in the experiment were analyzed using gas chromatography to determine the mechanism of CO 2 -improved oil production from tight matrix blocks. The results show that lighter components are extracted and produced early in the test. The results of these experiments validate the premises that CO 2 could be used to recover oil from a tight and unconfined matrix efficiently.

A technique is presented for estimating suspended sediment concentrations of turbid coastal waters with remotely sensed multi-spectral data. The method improves upon many standard techniques, since it incorporates analyses of multiple wavelength bands (four for Sea-viewing Wide Field of view Sensor (SeaWiFS)) and a nonlinear calibration, which produce highly accurate results (expected errors are approximately ¡10%). Further, potential errors produced by erroneous atmospheric calibration in excessively turbid waters and influences of dissolved organic materials, chlorophyll pigments and atmospheric aerosols are limited by a dark pixel subtraction and removal of the violet to blue wavelength bands. Results are presented for the Santa Barbara Channel, California where suspended sediment concentrations ranged from 0-200z mg l 21 (¡20 mg l 21 ) immediately after large river runoff events. The largest plumes were observed 10-30 km off the coast and occurred immediately following large El Niñ o winter floods.