Suction Potential Research Articles

New insights from serranid fishes on the role of trade-offs in suction feeding diversification

Suction feeding is central to prey capture in the vast majority of ray-finned fishes and has been well studied from a detailed, mechanistic perspective. Several major trade-offs are thought to have shaped the diversification of suction-feeding morphology and behavior, and have become well established in the literature. We revisited several of these expectations in a study of prey capture morphology and kinematics in 30 species of serranid fishes, a large, ecologically variable group that exhibits diverse combinations of suction and forward locomotion. We find that: (1) diversity among species in the morphological potential to generate suction changes drastically across the range of attack speeds that species use, with all species that use high-speed attacks having low capacity to generate suction, whereas slow-speed attackers exhibit the full range of suction abilities (this pattern indicates a more complex 'ram-suction continuum' than previously recognized); (2) there is no trade-off between the mechanical advantage of the lower jaw opening lever and the speed of jaw depression, revealing that this simple interpretation of lever mechanics fails to predict kinematic diversity; (3) high-speed attackers show increased cranial excursions, potentially to compensate for a decrease in accuracy; (4) the amount of jaw protrusion is positively related to attack speed, but not suction capacity; and (5) a principal component analysis revealed three significant multivariate axes of kinematic variation among species. Two of the three axes were correlated with the morphological potential to generate suction, indicating important but complex relationships between kinematics and suction potential. These results are consistent with other recent studies that show that trade-offs derived from simple biomechanical models may be less of a constraint on the evolutionary diversification of fish feeding systems than previously thought.

Threshold moisture content and matric suction potentials in expansive clays prior to initiation of cracking in pavements

Numerous low- to medium-volume roads constructed on expansive clay subgrades have experienced severe pavement cracking and premature loss of serviceability. These roads often become distressed due to volume change associated with seasonal moisture content fluctuation in the underlying soils. An attempt is made in this paper to study field moisture content and soil suction potentials of expansive subsoils, and investigate the potentials at which soil and pavement cracking occur. Two types of sensors were utilized to measure volumetric moisture content and matric suctions in the soils. These sensors were installed at three pavement subgrade sites in Fort Worth, San Antonio, and Paris Districts in Texas, USA. Test results show that site environmental conditions, such as climate and large trees near the test sections, have a strong influence on expansive soil movements and related pavement cracking. Three possible scenarios where pavement cracking could occur in the field, determined from analysis of the data, are outlined. Theoretical correlation developed between the laboratory-based shrinkage strain tests and changes in soil compaction moisture content was successfully used to estimate surficial crack widths in the field. Finally, methods to control desiccation cracking in the field are outlined.

Influence of interparticle forces on selective wet agglomeration

The influence of interparticle forces between primary particles, which include interaction force between dispersed particles in liquid calculated by DLVO theory and two kinds of forces caused by a liquid bridge of bridging liquid between particles, on selective wet agglomeration was investigated on the basis of the relationships between the results of separation efficiency obtained in author’s previous study and these interparticle forces. The first step of selective wet agglomeration is the collision between bridging liquid droplets and objective particles to be agglomerated. This collision is mainly influenced by the interparticle force calculated by DLVO theory. Incorporation of two objective particles, the second step in the agglomeration process, is influenced by liquid bridge force between objective particles. Growth to pellet-type agglomerates, the third step in the agglomeration process, is thought to be influenced mainly by aggregation force in the agglomerates by entry suction potential. The results of this study showed that selective wet agglomeration under the experimental conditions used in this study is influenced greatly by liquid bridge force and entry suction potential, which play major roles in the second step and third step, respectively, of the selective wet agglomeration process.

Sub-Bases Layers of Residual Granite Soil Stabilised with Lime

This paper describes the results of research carried out for evaluating the effects of hydrated lime, with and without chemical activators, for the modification (up to 2% lime) and stabilisation (more than 2% lime) of residual granite soils. The effects of the modification of granitic soils with the addition of 2% calcitic lime were studied; and the results of these modifications on particle size distribution, plasticity and strength gain of two soils with different clay fractions are reported. Furthermore, the effects on compressive strength when 6 and 10% lime were added for curing times up to 10 weeks were monitored. The effects of saturation of the stabilised soils were also studied, as well as the effects of a small percentage of NaCl on stabilised soils with and without saturation. This addition of NaCl proved to be highly beneficial and a better alternative than the addition of larger amounts of lime. Estimated loss of strength due to saturation of cured specimens appeared to be constant with curing time, indicating that this effect is due to loss of suction potential.

Vortex Identification Methodology for Feed Insertion Guidance in Fluid Mixing Processes

A vortex tracking methodology is developed to determine the precessional frequency and the characteristics of macroinstability (MI) vortices. The methodology is compared with other techniques, frequency analysis and correlation coeffcient, which are most commonly used to assess periodicities in a flow. Two sets of experiments were carried out, 2D PIV and two-point LDA, in two different scaled vessels of diameter 80 mm and 294 mm. The MI characteristics were studied for two different Re (i.e., 32 000 and 3200) by correlating the vortex intensity (vorticity and pressure suction) with its radius at different axial positions. This study provides relevant data for the optimisation of mixing time as it indicates ‘preferred’ positions, on the path of the MI vortex, where the insertion of a second phase should take place in order to fully exploit the suction potential of the MI vortex.

Free Energy of Water-Suction-in Filter Papers

Abstract In this paper, a critical evaluation of the filter paper method is presented. The paper evaluates wetting and drying filter paper suction calibration and total and matric soil suction measurement techniques using the filter paper method. Calibration of the method was investigated by evaluating the processes of wetting and drying the filter papers through vapor transfer and of wetting and drying the filter papers through fluid transfer. Recent research shows that different calibration curves result from two different experimental measurement programs (vapor transfer, no contact method and fluid transfer, contact method) for total and matric components of suction. In this study, a filter paper wetting curve was constructed using osmotic suction potentials of sodium chloride (NaCl), ammonium chloride (NH4Cl), calcium chloride (CaCl2), and sodium sulfate (Na2SO4) salt solutions and Schleicher & Schuell No. 589-WH filter papers. Equilibrium time and temperature were two weeks and 25°C with ±0.1°C accuracy, respectively. The adopted laboratory testing protocol shows that suction measurements as low as 50 kPa can be made reliably using the wetting calibration curve obtained in this research study. The calibration curves obtained from the processes of drying the filter papers through vapor transfer (from salt solutions) and drying and wetting the filter papers through fluid transfer (pressure plate type devices) were evaluated based on recently published literature. Although there is hysteresis between the wetting curve with salt solutions and the drying curve with pressure plates, the marked differences between the curves at very low suction levels may not be explained with hysteresis.

Prediction of Unsaturated Hydraulic Conductivities of Mesh-Wicks Based on the Dimensionless Capillary Suction Potential

Combining a capillary bundle model and the functional form of a j-function has deduced the relative hydraulic conductivity of a mesh-wick as a function only of the reduced saturation. The empirical expression of the relative hydraulic conductivity has also provided steady-state saturation profiles observed in a wick with infiltrating liquid percolating to a liquid table.The final average residual saturation can be reasonably estimated from a calculation of a newly defined capillary number, which takes into account the final equilibrium saturation profile as well as the j-function.

Mesure de la masse volumique de l’eau interfoliaire dans les smectites ; application aux courbes capillaires

The purpose of this work is to study the particular physical properties of interlayer water in clay-water systems. Five smectites, in a powder form, are studied at different hydric potentials in a range of relative humidity between 5 and 97 %. These relative humidities correspond to a suction potential between 400 MPa and 4 MPa. Regardless of these RH conditions, the interaggregates space is never saturated with water. We also observed that the basal spacing d∞ of the clay sheets changes in accordance with the evolution of water content. These facts lead us conclude that the interlayer space is the main location where the hydratation occurs, i.e. where we expect the physical properties such as the water density to be different from bulk water. The density of the interlayer water and the solid density are simultaneously measured by means of a helium pycnometer. When measuring the total volume of a powder with this method, a correction is needed to take into account the volume occupied by water. Corrections using a density of the water equal to that of pure water did not give satisfactory results. To attain an agreement with the experimental results, we had to recalculate the density of the interlayer water. These values are found to lie between 1,14 and 1,18 Mg/ 3 for the studied clays and depend on the population of exchangeable cations present in the interlayer space, especially on the sodium/calcium ratio. The consequences of a such water density upon suction curves (as a decrease of 10-15% on the saturation degree) are discussed.

Microwave-assisted surface modification of calcium bicarbonate

Surface modification of calcium bicarbonate powder with isopropyl triisostearoyl titanate (TTS) by microwave-assisted heating was studied in the present work. The features of microwave treated powder show obvious superiority to those of powder samples treated by traditional surface modification method and of untreated calcium bicarbonate —in suspension turbidity, suction potential, contact angle with water, and mechanical properties of their composites with PVC resin.

Dependency of tortuosity on capillary suction potentials of compressible and incompressible particulate beds

Measurements of capillary suction potential in drainage processes have developed a capillary bundle model, which makes it reasonably possible to deduce a dimensionless capillary suction potential by considering the dependency of tortuosity. The capillary suction potential has been found to depend strongly on the tortuosity, especially for the compressible filtered cakes. The tortuosity determined empirically using the capillary model provides the dimensionless capillary suction potential which can correlate to the reduced saturation for both incompressible particulate beds and compressible filtered cakes. The final average residual saturation can be accurately estimated from calculation of a newly defined capillary number, which takes into account the final equilibrium saturation profile. The calculated results agree well with experiments observed for incompressible particulate beds drained under gravity.

Dependency of Tortuosity on Saturated and Unsaturated Flow within Mesh-Type Wicks.

Measurements of capillary suction potential of mesh-type wicks have developed a capillary model, which reasonably makes it possible to predict unsaturated hydraulic conductivity by considering the dependency of tortuosity on the saturation level, as well as to deduce a dimensionless capillary suction potential. The capillary model has also been provided to predict saturation profiles observed in a wick through which liquid flows at a constant infiltration rate and draining to a liquid table.The friction factor cf determined from the observed capillary potential has been related to the Reynolds number Re by cfRe = constant, which experimentally proved independent of the mesh woven-types and mesh layers consisting of a wick. The estimated cfRe value demonstrates its availability to predict the saturated hydraulic conductivity of mesh-type wicks.

Influence of Organic Matter in Soils on Radar-Wave Reflection: Sedimentological Implications

ABSTRACT Soils are excellent reflectors of ground-penetrating radar (GPR) signals because of the ability of organic matter to hold water. In this paper, GPR profiles of an eolian sedimentary succession are combined with textural, dielectric, and moisture-retention characteristics to illustrate the influence of soil moisture on radar-wave reflection. Organic matter in this succession varies strongly, from ;lt 0.15% for clean sand to 7% for the most prominent soil, whereas grain-size distributions are comparable. Moisture-retention curves show a complex relationship between suction potential (pF) and volumetric water content (). As a result of their uniform pore-size distribution, clean sand and weakly developed soils with ;lt 1% organic matter experience a sudden loss of water between pF 1.5 and pF 1.8, going directly from saturated to almost dry conditions. In contrast, the most prominent soil shows a more gradual decrease in with increasing suction potential. It follows that the dielectric contrast between clean sand and this soil increases sharply above pF 1.5, reaches a maximum value at field-capacity conditions, and then decreases slowly. Synthetic GPR images for different suction potentials show that field-capacity conditions, when reflection coefficients are high, are favorable for tracing one single soil. Dry sediments are preferable when imaging widely spaced soils, whereas saturated sediments are best when imaging closely spaced soils.

Effect of capillary suction potential on agglomeration of coal in water

Effect of capillary suction potential on agglomeration of coal in water

Study of swelling-shrinkage regularity of montmorillonite crystal and its relation with matric suction

The swell-shrinking mineral of saturated and unsaturated expansive soil has important effect on engineering mechanical behavior. Based on the swelling-shrinkage change regularity of montmorillonite crystal in this paper, the actions between various interlayers of montmorillonite crystal are generally summarized as two kinds of action potentials-shrinkage potential and swelling potential. Moreover, through the experimental research and analysis, the expression formula for variations of the swelling potential and shrinkage potential with interlayer distance is presented, and the regularity of matric suction variations with interlayer distance is also obtained for unsaturated expansive soil. It may provide a new theoretical basis and research path for further research on the swelling-shrinkage mechanism of expansive soil and matric suction potential of unsaturated soil.

石炭の水中造粒への毛管吸引圧の影響

The effect of capillary suction potential on the agglomeration of coal in water was investigated at various concentrations of added surface active agent and addition ratios of bridging liquid. Agglomeration was carried out by injecting castor oil as a bridging liquid into the suspension, which consisted of disperse medium and ground coal. An aqueous solution of 10-2 mol · l-1-NaCl was used as the disperse medium, and sodium oleate was added to the solution as an additive surface active agent. The main results of this work are as follows:1) The addition of sodium oleate to the disperse medium modified both the contact angle of the bridging liquid on coal particles and the interfacial tension between the bridging liquid and the disperse medium and therefore affected the agglomeration phenomena.2) The equilibrium agglomerate diameter increased as the capillary suction potential increased. Based on a model in which the equilibrium agglomerate diameter is determined by the balance between the cohesive force caused by capillary suction potential and the destructive force caused by agitation, an empirical equation to determine relationship between the equilibrium agglomerate diameter and the cohesive force was obtained.

湿式球形造粒における平衡造粒粒子径の検討

Equilibrium agglomerate diameter in wet spherical agglomeration was investigated at various concentrations of added surface active agent and the addition ratios of bridging liquid. Spherical polyethylene particles, castor oil and sodium oleate were used respectively as the raw particles, the bridging liquid and the surface active agent. The addition of surface active agent to disperse medium modified both the interfacial tension between bridging liquid and disperse medium and the contact angle of bridging liquid on raw particles, and therefore affected the agglomeration phenomena. The relationship between the equilibrium agglomerate diameter and the factors affecting wet spherical agglomeration was well explained by the theoretical model, which takes into account the balance between the cohesive force by capillary suction potential and the destructive force by agitation.

Influence des phénomènes d'hystérésis sur les propriétés hydriques de matériaux poreux: Comparaison de deux modèles de simulation du comportement thermohydrique de parois de bâtiment

Porous materials hysteretic moisture characteristics : influence on water content distributions in buildings walls. Comparison of two simulation models. Two models for determining the temperature and moisture distributions within a wall are presented. The first one is a direct application of the classical Philip and de Vries model. The second one, using the suction potential, is derived from Milly's researches and is more efficient because it allows the hysteresis phenomena to be taken into account. First, the different equilibrium and transfer parameters used in the models are reviewed. Indications are given on how they can be experimentally determined and results for two cement pastes and a cellular concrete are illustrated. Then, calculation results of water content distributions for the two models are presented for an homogeneous cellular concrete wall in steady environmental conditions. In that particular case, the two models estimations are in good agreement despite different numerical treatments and experimental procedures. Using Milly's model with cyclic boundaries conditions, a significant influence of hysteresis phenomena is clearly shown.

Experimental Analysis of Three Dimensional Consolidation Behavior in Slip Casting

Consolidation behavior in slip casting of a well-dispersed alumina slurry was experimentally analyzed, using wall-sealed, bottom-sealed and unsealed cylindrical plaster molds. Solid front (the interface between the consolidated layer and slurry in the cavity) and liquid front (the interface between the dry and saturated part in the plaster) were simultaneously measured. Both fronts grew not in one dimension but in three dimensions, depending on the type of mold. There was a similarity in the growth patterns between solid and liquid fronts. It was found that three dimensional suction potential of the plaster mold caused the curved growth patterns. The region deposited at early stages of casting yielded a higher bulk density than the region deposited at late stages of casting. The mean bulk density and homogeneity of cast bodies were also dependent on the type of mold.

Expansion Potential of Compacted Fine-Grained Soils Using Suction Measurements

Abstract Fine-grained soils in arid climates are most often unsaturated. If such soils have a swelling potential, their expansive pressure must be determined for structural design. Hitherto employed swelling test methods are time consuming and not reliable. Testing methods based on suction potential measurements are being introduced in order to evaluate the expansive potential. Swelling test results on three fine-grained soils are described in the paper. Two testing systems were used: (1) a traditional method of constant soil volume and (2) a proposed method utilizing suction pressure measurements. The tested soil samples were characterized by different consolidation initial-moisture-content conditions. The test results presented herein were used to develop a mathematical relationship between expansive pressure and suction pressure for a given soil. A design procedure for estimating swelling pressure is proposed in the paper.

Soil Suction‐Potential Model

A suction‐potential model based on the diffusion equation is proposed whereby the suction is predicted at all times and depths in terms of a parameter K and the initial values of suction β0 The model shows that the suction ratio decays exponentially with time. The exponential decay rate is not uniform throughout the expansive soil, but it increases with decreasing distance to the water source. Analysis reveals that the prediction error will not exceed 25% even if K value increases by 100%, suggesting the validity of the model in providing an adequate means for suction determination. Furthermore, close agreement is found between laboratory observations and the theoretical behavior. However, the theoretical estimate of the average suction potential does not agree well with the field observation. The discrepancies may be attributed to the heterogeneities of the soil and to the simplified boundary conditions adopted in the theoretical model.