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The aim of this study has been to demonstrate the way of determination of drainage discharge by the method of De Zeeuw-Hellinga in the transient drainage flow conditions. For comparison and verification of numerical experiment of calculation of drainage discharge by equation of De Zeeuw-Hellinga with measured daily values of drainage discharge was selected subsurface pipe drainage system in experimental drained area, placed in the local city park next to the Mseno Dam, in the city of Jablonec nad Nisou, Czech Republic. The results showed a good conformity between calculations and measured data, the differences between De Zeeuw-Hellinga’s approximations and measured daily values of drainage discharge fluctuated from 0.6 (mm.day-1) to zero, and confirmed that the De Zeeuw-Hellinga’s formula is a suitable tool for approximation of the drainage discharge in the transient flow conditions. It was confirmed again that De Zeeuw-Hellinga theory is also applicable for the shallow subsurface pipe drainage system.

Geological storage of CO2 in deep saline aquifers is achieved by injecting CO2 into aquifers and displacing the brine. Although most of the groundwater is displaced, some residual groundwater remains in the rock pores. We conducted experiments to investigate the formation process of residual water. Rock samples were saturated with brines of different concentrations. CO2 was injected into the samples at aquifer temperature and pressure, and the drained water was measured. The results show that the groundwater drainage was slower and the irreducible water saturation was higher with higher brine concentration. The process of drainage can be classified into three stages according to the drainage flow rates: piston drainage, portable drainage, and dissolved drainage.

Presented at the Protections 2016: 2nd international seminar on dam protection against overtopping: concrete dams, embankment dams, levees, tailings dams held on 7th-9th September, 2016, at Colorado State University in Fort Collins, Colorado, USA. The increasing demand for dam and levee safety and flood protection has motivated new research and advancements and a greater need for cost-effective measures in overtopping protection as a solution for overtopping concerns at levees and dams. This seminar will bring together leading experts from practice, research, development, and implementation for two days of knowledge exchange followed by a technical tour of the Colorado State University Hydraulic Laboratory with overtopping flume and wave simulator. This seminar will focus on: Critical issues related to levees and dams; New developments and advanced tools; Overtopping protection systems; System design and performance; Applications and innovative solutions; Case histories of overtopping events; Physical modeling techniques and recent studies; and Numerical modeling methods., Includes bibliographical references., The technology of wedge shaped blocks (WSB) for spillways has had a rising development through the last forty years, and has proved its reliability for practical applications with spillways executed during the last decade. Ongoing additional research aims to complete the understanding of the hydraulic behavior, improve current design criteria and make this technology available to practitioners, in order to consider this type of spillway together with the conventional alternatives when designing an embankment dam spillway. A summary is here shown of recent research performed by the consortium formed by the research organizations: Research Group in Dam Safety (SERPA) of the Technical University of Madrid (UPM) and the International Center for Numerical Methods in Engineering (CIMNE) and the company PREHORQUISA. Even though the experimental campaign has not been completed, some preliminary conclusions can be addressed about the developed pressures along the block tread and the leakage flow from the joints among blocks and the drainage holes.

In order to control the seepage and eliminate the adverse effects, influencing factors of drainage in engineering are discussed in this paper. The drainage holes are simulated by rod element to study the influence of drainage performance on angle and length. Compared the drainage performance of drainage galleries in different location, the optimal assembly is obtained. Meanwhile, drainage performance is analyzed by different permeability coefficient and anisotropy of rock and soil mass. The results show that: (1) Drainage flow of small angle and short drainage hole is close to big angle and long one, the small angle flows more than the big angle when increasing the same length. (2) Shallow drainage galleries can significantly drop the free surface and the deep one can greatly decrease the pore water pressure. Drainage galleries built at the upstream side and bottom, as the optimum assembly, can enormously change the seepage field. (3) For anisotropy materials, the horizontal drainage performance is better than vertical when Ky/Kx decreases. On the contrary, vertical is superior to the horizontal. Increasing vertical permeability coefficient is benefit to drainage.

This experimental study examines the two phase flow structures of airflow pressures for annular flow through a 900 bend, with and without, a vortex fin for drainage applications. The superficial li...

Management of pancreatic pseudocyst is controversial.Surgical therapy has been clasically considered the treatment of choice for those pseudocysts. However, several studies have shown good results with percutaneous drainage. Percutaneous drainage can be performed easily, with minimal complication and may facilitate the resolution of a pseudocyst. We presented a case of a 20-year-old boy who sustained blunt abdominal trauma following motorvehicle accident. A large pancreatic pseudocyst developed within 3 weeks after the accident. Percutaneous drainage under ultrasound guidance was performed. The drainage flow decreased gradually until ceasing, and the pseudocyst disappeared.

Dense observations and numerical experiments were carried out to estimate the modification of mesoscale circulation, particularly cold drainage wind. It was confirmed that nocturnal drainage flow can develop on clear calm summer day and change due to orographical forcing and the heterogeneity of heat flux induced by the discontinuity of land-use. The temperature of nocturnal drainage flow at Sungji Valley, Busan Korea, tended to increase as it passed over the urban surface due to anthropogenic heat. The increase in temperature reached 2.9 K at night. The roughness associated with the exchange of momentum flux alone and the pass of nocturnal drainage flow is important for modifying the characteristics of flow Numerical simulations carried out under various surface conditions showed good agreement with the observations. Urban heat fluxes from the surface during the day are fundamental causes of the changes in the urban mesoscale circulation. In addition, the impact of a discontinuity of surface heat flux on mesoscale flow modification tends to be greater at night than during the day because the direction of urban surface heat fluxes at night is different from that in rural areas. In addition, the criterion to estimate the increase in temperature nocturnal drainage flow was also proposed, and provided results that generally agreed with the numerical results.

Observations are analyzed to explain an unusual feature of the nighttime atmospheric structure inside Arizona’s idealized, basin-shaped Meteor Crater. The upper 75%–80% of the crater’s atmosphere, which overlies an intense surface-based inversion on the crater’s floor, maintains a near-isothermal lapse rate during the entire night, even while continuing to cool. Evidence is presented to show that this near-isothermal layer is produced by cold-air intrusions that come over the crater’s rim. The intrusions are driven by a regional-scale drainage flow that develops over the surrounding inclined Colorado Plateau. Cold air from the drainage flow builds up on the upwind side of the crater and splits around the crater at low levels. A shallow layer of cold air, however, spills over the 30–60-m-high rim and descends partway down the crater’s upwind inner sidewall until reaching its buoyancy equilibrium level. Detrainment of cold air during its katabatic descent and compensatory rising motions in the crater atmosphere destabilize the basin atmosphere, producing the observed near-isothermal lapse rate. A conceptual model of this phenomenon is presented.

To feedback plant water requirement into control of solution supply in hydroponics, we developed a method to measure drainage flow rate continuously. Drainage accumulates in an apparatus which we have developed, and its weight is measured continuously by a balance. Continuous measurement of drainage makes real-time monitoring of water uptake by plants practicable. We examined the usefulness of this method for controlling the supply of nutrient solution in an aeroponics of cucumbers (Cucumis sativusL.) . We compared two methods of controlling the nutrient solution supply. As a new method, to determine the amount of solution supply on the following day, we fit an equation relating water uptake to solar radiation. As a conventional method, solution was supplied whenever the integrated solar radiation reached 0.0926 MJ m-2 and fed back daily leaching fraction of a previous day into the control. In the first half of the experimental period, the water uptake in the new method was higher than the conventional method. In the second half, water uptake was similar for the two methods. Fruits yield of the new method was significantly higher than the conventional method.

The subsurface total drainagequantity is one of the most importantindicators for the drainage policy of watermanagement. The methods of estimationof the subsurface total drainage quantityunder unsteady state drainage flow maybe different in consideration of the timeduration of the process and in relation tothe type, quality and quantity of the data used.

Environmental contamination with heavy metals and radionuclides remains a major problem worldwide. The current clean-up methodologies are based on energy-intensive engineering processes, which are disruptive and costly. A new universal technology targeted for the permanent enclosure and fixation of nuclear and other extreme hazardous metallic wastes in subsurface sites is needed. Such technology will be useful in treating contamination at many sites in the U.S., with specific applications to Department of Energy (DOE) sites. Biopolymers are potential tools for such an innovative technology. Biopolymers have repeated sequences, and therefore provide ample opportunity for chemical reactions with metals, soil particles, and other biopolymers. They also have the additional ability of creating cross-linking interpenetrating networks that can encapsulate the contaminants. Based on this concept, in the present work five biopolymers (xanthan, chitosan, polyhydroxy butyrate, guar gum, polyglutamic acid) were inves...

SUMMARY This study documents the aire ow within major Alpine river valleys in the presence of precipitation. The analysis seeks a conceptual understanding of the effect of rain on the valley e ow. Ground-based and airborne Doppler radar and surface data from the Mesoscale Alpine Programme show that during persistent rainy periods the subsidence caused by melting and evaporation of precipitation particles contributes to the formation of a down-valley e ow. This down-valley eow opposes moist southerly e ow aloft, which is lifted over the topographic barrier and in which precipitation particles are formed.

In the design of a drainage system, allowable drainage flow quantity (drainage capability) is defined for each pipe diameter in order to prevent seal water from breaking. In Japan, SHASE-S 218 (Heating, Air-Conditioning, and Sanitary Standard) stipulates the evaluation standard for drainage capability. Regardless of the presence or absence of connection of the traps, there are two types of test criteria. One is that pressure in the pipe should fall within ±400 Pa, and the other is that the seal loss should be less than 25 mm. Nevertheless, recent studies revealed that the connecting of traps attenuates pneumatic pressure in pipes and causes a tendency of the power spectrum distribution to change. This phenomenon may be attributable to the fact that seal water vibration is a response phenomenon to pneumatic pressure vibration, and that they affect each other. In view of this, we conducted discharge experiments based on SHASE-S 218 with and without traps (including water-saving toilet bowl (hereinafter, referred to as “WC”) using a real size drainage experimental system to clarify how the connection of WC might influence pneumatic pressure. We revealed that as the number of toilets connected to the drainage system increases, the pneumatic pressure and seal water loss decrease.

The Penn State–NCAR mesoscale model MM5 is used to simulate and better understand the wind observations in the Kali Gandaki Valley reported in the first part of this paper. The Kali Gandaki River originates in Nepal near Tibet, flows southward through the Mustang Basin, crosses the Himalayas in a gorge, and descends to the lowlands of Nepal. Extremely strong diurnal upvalley flow in the gorge and the basin alternates with rather weak drainage flow in the night. As proposed in Part I, the Mustang Basin and the Tibetan Plateau can be considered as an elevated heat source driving the upvalley flow during the day. However, the extreme strength of the diurnal upvalley winds and the order-of-magnitude asymmetry between day and night cannot be explained with a simple plateau circulation theory. The model is successful in simulating almost all aspects of the observations. The simulations strongly suggest that the observed acceleration of the upvalley winds near the entrance to the Mustang Basin is linked...

The evolution of a foam is determined by drainage flow of the continuous (liquid) phase and coarsening (aging) of the dispersed phase (gas bubbles). Free-drainage experiments with slow- and fast-coarsening gases show markedly different dynamics and elucidate the importance of the coupling of the two effects. Strong coarsening leads to drainage times that are shorter (accelerated drainage) and independent of the initial liquid content (self-limiting drainage). A model incorporating the physics of both drainage and diffusive coarsening shows quantitative agreement with experiment.

The diurnal wind system of the Kali Gandaki Valley in Nepal was explored in September and October 1998 in a field campaign using pilot balloons as the main observational tool. This valley connects the Plateau of Tibet with the Indian plains. The river crosses the Himalayas forming the deepest valley on Earth. Intense upvalley winds blow up this valley during the day. Observations were made along the river at various spots selected between the exit point from the Himalayas and the source close to the Plateau of Tibet. The strongest upvalley winds were found between Marpha and Chuksang with typical speeds of 15–20 m s−1. The upvalley wind sets in first at the ground but an upvalley wind layer of 1000–2000-m depth forms quickly after the onset. This deep inflow layer persists up to Lo Manthang, a town located a few kilometers south of the Plateau of Tibet. Deceleration in the late afternoon and evening also appears to commence near the ground. Weak drainage flow forms late in the night. The causes o...

The flow conditions within multi-storey building drainage networks may be characterised as unsteady free surface flows and as such may be analysed and simulated by the use of the method of characteristics to solve numerically the governing equations of continuity and momentum. However the application of such simulations must take into account the possibility of defective system installation and must be able to predict the wave attenuation following appliance discharge and the consequent effects upon solid transport due to system defects caused by faulty installation or the development of obstructions to the flow. This paper presents both a summary of a detailed survey of defects in installed building drainage networks and the development of appropriate boundary conditions that allow the method of characteristics based computer simulation to accurately predict the effect of defects on system performance. The introduction of drainage simulations capable of providing design advice under the real conditions represented by this study is particularly timely in view of governmental pressure for water conservation and the introduction in 1998 of the new Water Regulations to replace the Water Bye-Laws that will introduce reduced and dual flush w.c. operation, together with reduced shower and other appliance flows.

Infiltration experiments with intensities varying from 4.1 x 10−6 to 2.8 x 10−5 m s−1 were conducted on a column of undisturbed soil. Flow was investigated using kinematic wave theory. The approach was first applied to the drainage curve of outflow. In this case, preferential flow occurred during intermediate infiltration rates. The approach was further applied to soil moisture variations at three depths of the column. The wetting front dispersion increased with depth according to the analysis of mobile soil moisture contributing to total flow, whereas the analysis of mobile soil moisture contributing to rapid flow indicated flow through macropores. The kinematic wave model simulates reasonably well both measured drainage of outflow and of soil moisture. A simple method was used to separate mobile soil moisture contributing to rapid flow and that contributing to diffusive flow. The validity of the model was evaluated by water balance comparison, with particular attention given to the distinction ...

This paper describes the simulation of the most important characteristics of the flow and temperature fields observed during the tracer release of the 1990 TRANSALP campaign. The goal of the campaign was to follow the tracer from Leventina Valley to the other side of the Alpine range to investigate whether a re-circulation process could occur due to the valley and mountain breezes. Model output is compared with observations of wind and temperature over an entire day (29 September 1990). Meteorological measurements were obtained at a number of ground stations. Vertical wind and temperature profiles were also available. Model initialization was performed using airborne meteorological measurements and profiles from the synoptic station of Payerne. RAMS results correctly describe the generation of the drainage flow during the night and the successive formation of the valley breeze due to the difference in temperature gradients in the various valleys of the domain. Simulated windfields are in general more accurate during the daytime than during the night hours, since vertical variability in stable conditions is more difficult to reproduce.

This paper explains the method of the hydraulic calculations of the landfill leachate rate from the internal landfill drainage system, placed at the bottom of the domestic waste sanitary landfill, based on the drainage theory of the De Zeeuw-Hellinga Equation, under the non-steady saturated drainage flow conditions. The results were verified and compared by the actual data from the sanitary landfill of domestic waste in Osecna location, situated in the Northern Bohemia, Czech Republic.

A month-long field program to study the springtime katabatic wind confluence zone (where katabatic winds converge) has been carried out near Siple Coast, West Antarctica. Based on previous observations and numerical studies, two surface camps, Upstream B (83.5°8, 136.1°W) and South Camp (84.5°S, 134.3°W), were established. Ground-based remote sensing equipment (sodar and RASS), along with conventional observations, were used. Combining the analyses of surface observations and wind and temperature profiles at the above camps, the following picture for the cross-sectional structure of the confluence zone emerges. A relatively cold katabatic airflow, which probably comes from Fast Antarctica, occupies the layer between the surface and roughly 500 m ACL. Low-level jets are present below 200 m AGL and are stronger near the Transantarctic Mountains. Diurnal variation is present in this cold drainage flow and decreases toward the Transantarctic Mountains. Weak-inversion-layer tops are found near 500 m A...

Laboratory experiments were conducted to simulate the diurnal heating-cooling cycle in the vicinity of a ridge of constant cross section. In the model the fluid is a water solution stratified with salt to simulate the background stratification of the atmosphere. The flow is driven by recirculating water of a controlled temperature beneath the model; the model surface temperature is thus varied in a specified way to simulate the surface heating by solar insolation during the daytime hours and surface cooling by radiation during the nighttime. The pertinent similarity parameters are shown to be Gc, for daytime convective flow and Gd for nocturnal flow; here Gc = Hb/Hc, Gd = Hb/Hd, where Hb, is the mountain height, Hc the neutral buoyancy height of free convection. and Hd the characteristic thickness of the nighttime drainage flow. The model demonstrates some of the principal features of thermally driven mountain circulations, including daytime upslope winds and nocturnal downslope drainage flows. T...

The nighttime local wind and accumulation of cold air over the Kanto Plain in Japan were investigated with a three-dimensional hydrostatic numerical model under the condition of no synoptic pressure gradient. Numerical results strongly support the hypothesis that cold air accumulated in the western portion of the plain owing to the convergence of drainage flow from the mountain slopes in the northern and western parts of the plain. The accumulated cold air generated a deep surface inversion layer over the region, as suggested by observations. The cold air drained along three large rivers located in the plain after 1900 LST, when the daytime valley winds ceased. The heat flux between the surface and the atmosphere was exchanged mainly over the relatively steep slopes of forest-covered mountains, although the drainage flow there was not very strong. The low-temperature area generated in the center of the Kanto Plain could be distinguished even after noon the following day.

Procedures for drainage basin delineation and modeling of drainage flow accumulation are provided for single instruction stream, multiple data stream (SIMD) computers. Performance statistics were gathered from a series of windows on a DEM and analyzed for an implementation of the procedures, written in C ∗ and executed on a Thinking Machines CM-5 in SIMD mode. Results of the analysis show that the SIMD implementation completes execution in less than one-half the time of a comparable sequential implementation when both are run over the largest window. The results also show that execution times for the SIMD implementation initially increase linearly with the ratio of virtual processors to physical processors.

Objectives To examine features of drainage flow and to determine whether the drainage period could be safely reduced in continuous ambulatory peritoneal dialysis (CAPD) patients. Design Open nonrandomized prospective study in CAPD patients. Setting The kidney center in a tertiary care university hospital. Patients Fourteen CAPD patients with good catheter function. Interventions Drainage flow pattern was studied using a 2-L dialysate. The drainage period was reduced from 28 minutes (mean) to 10 minutes throughout a short-term, 2-month study period and a long-term, 6-month study period for 10 patients. Main Outcome Measures Ultrafiltration volume, body weight, and peritoneal clearance. Results A kinetics analysis of the drainage period and volume indicated a positive linear correlation with two different slopes: one for rapid drainage for the first 5–7 minutes and one for subsequent slow drainage. The effluent exceded 80% in the former period. Ultrafiltration volume and body weight showed no change due to the reduction. Improved peritoneal clearance of small molecular substances could not be confirmed despite a 5% increase in the effective dialysis period. Nearly all patients were satisfied with the reduction and desired its continuation. Conclusions Ten minutes is a sufficient drainage period for most CAPD patients with a 2-L dialysate volume. This may possibly allow an increase in daily activities and an effective peritoneal membrane dialysate contact period.

The formation of huge amounts of drainage water is characteristic of irrigated agriculture in the Central Asian region. During the intensive development of new irrigated lands, drainage water amounted to 39–40 km3out of a total surface water resource of 110–115 km3. In recent years, a decrease in drainage flow volume to 32–34 km3 has been observed due to forced reduction of specific water supply per irrigated hectare because of excessive expansion of irrigated areas, development of industry and other water-using sectors of the economy, and population increases.

Perforated draintubes have, in many places, supplanted the use of draintiles in drainage systems of agricultural lands, airports, structural foundations, etc. This indicates that there is a need to obtain analytical solutions of the drainage flow rate for perforated draintubes. By using a series solution of Laplace's equation and techniques of solution of dual trigonometric series, a formula for the flow rate into a draintube buried in a water-saturated soil medium is developed. The flow rate into a draintube depends on numerous characteristics such as the hole size, the number and spacing of holes, the drain size and depth. Graphs showing the variation in delivery ratio with respect to geometric characteristics of draintubes are presented.

A method to determine the soil hydraulic conductivity via an internal drainage experiment is presented. Identifying the parameters of the hydraulic conductivity is achieved by solving an inverse global optimization problem that uses the water contents measured at different depths and times as matching flow variables. The optimization procedure is combined with a recently developed analytical model for the water content propagation, which essentially assumes that the flow is gravity-driven. A crucial (from the identification point of view) parameter of such a model is the initial position z W of the draining front, determining the interface between the wetted and dried zone. By using an evolutionary algorithm specifically developed for this problem, it is shown that if information upon z W is not a priori available, the identification of the hydraulic conductivity is not possible. However, assuming that z W is known (i.e. measured), and by dividing the model variables by z W , the optimization is able to fully identify the soil hydraulic conductivity. Finally, in order to show the robustness of the proposed approach, it is shown that the method leads to very good estimates of the hydraulic conductivity even if data are noise-affected, provided that the optimization procedure is coupled to the (Tikhonov) regularization approach.

The characteristics of tributary drainage flow in stable, nocturnal conditions in three closely located tributaries are compared. The orientation of the tributaries with respect to Kimball Creek, into which they drain, appears to be a controlling factor in the tributary flow. In particular, oscillations in the drainage flow are found to be weakest and drainage mass per unit area greatest in the tributary most closely aligned with the main canyon.

[1] This study focuses on observations of the sea and land breeze circulations in the southern Arabian Gulf. During the summer months, the Indian monsoon creates light northwesterly winds over the Arabian Gulf, allowing for the formation of thermally driven circulations. Observations from a network of stations are used to develop a wind climatology for the Arabian Gulf region. Characteristics of the sea and land breeze circulations, such as onset time, duration, and horizontal and vertical extent are described. The dense network of surface stations in the United Arab Emirates (UAE) allows for a fine-scale observational study in this region. It is found that the sea breeze occurs during all seasons of the year in this region. It occurs in the late afternoon and continues through the evening. A land breeze sets in during the night. Surface offshore winds in the land breeze are strong probably due to drainage flow down the inland hills.

Wind and temperature profiles and corresponding acoustic sounder data collected in September 1982 are presented for nocturnal drainage flow and inversion breakup in two Alberta mountain valleys. The results show that the diurnal amplitude of average valley air temperatures for the Canyon Creek Valley is greater than the Elbow River Valley for four case days. The two-dimensional topographic amplification factors for both valleys show that this difference can be explained on the basis of differing valley geometry. The bottom half of the Canyon Creek Valley drainage flow had a weak inversion (1–2 K/100 m) with the top half of much greater strength (7 K/100 m). The Elbow River Valley drainage flow had an inversion strength of 2.9 K/100 m which was invariant with height. In the Canyon Creek Valley when the ridgetop winds had an up-valley component, the maximum down-valley wind speed occurs at 30%–40% of the drainage depth as opposed to 50%–60% when there is no up-valley component. There is also a line...

The variations of Σθ and ΣΦ in the drainage flow in the Brush Creek valley of western Colorado are investigated using data from Doppler acoustic sodars and instrumented towers. The data were obtained on two experimental nights during the 1984 ASCOT field study. There is good agreement between the Σ variations derived from low-level observations of the sodars and those derived from the towers located throughout the valley. The observed hourly average Σθ and ΣΦ in the nocturnal drainage flow are about 20 ° to 25 ° and 5 °, respectively; these values are much larger than those generally observed over flat terrain during nighttime stable conditions. After sunrise (about 0600 MST), as the valley warms and the flow direction changes to up-valley, these parameters increase sharply to their peak values at about 0800 MST and then decrease to their normal daytime values after about two hours.

Objectives To evaluate the impact of percutaneous nephrostomy catheter configuration on drainage flow and retention strength. Methods The Cook nephrostomy 16F (symmetric balloon), Bardex Council 16F (eccentric balloon), Microvasive Flexima 14F (pigtail), and Bardex Malecot 16F (flange) nephrostomy catheters were attached to an artificial renal pelvis (12-in.-round latex balloon). The balloon was subsequently filled with either 60 mL of water or orange juice with pulp, and gravity drainage of this fluid was recorded as flow into a flowmeter. Using a Force Five Model FDV-100 force gauge, the retention strength was tested by measuring the force required to pull the nephrostomy catheter through an 8-mm hole in a 35-mm-thick biologic tissue specimen (bologna). Results The maximal flow rate using both orange juice and saline was significantly greater for the Cook nephrostomy than for the Microvasive Flexima, Bardex Malecot, and Bardex Council catheters (P ≤0.016). The average flow rate using saline for the Cook nephrostomy catheter was significantly greater than for all other catheters (P ≤0.02) and was significantly greater than for the Microvasive Flexima and the Bardex Council catheters (P ≤0.036) using orange juice. The retention strength was strongest for the Cook nephrostomy catheter (3.41 ± 0.14 lb) compared with the Bardex Council (1.75 ± 0.1), Microvasive Flexima (1.35 ± 0.3), and Bardex Malecot (0.29 ± 0.03) catheters. In addition, the Microvasive Flexima catheter resulted in greater maceration of the biologic tissue after forceful dislodgement. Conclusions The results of this study have demonstrated that the Cook nephrostomy catheter combines strong drainage flow and strong retention strength during in vitro testing. Clinical evaluations of the ease of use and patient comfort are warranted.

When two immiscible liquids that coexist inside a porous medium are drained through an opening, a complex flow takes place in which the interface between the liquids moves, tilts and bends. The interface profiles depend on the physical properties of the liquids and on the velocity at which they are extracted. If the drainage flow rate, the liquids volume fraction in the drainage flow and the physical properties of the liquids are known, the interface angle in the immediate vicinity of the outlet (theta) can be determined. In this work, we define four nondimensional parameters that rule the fluid dynamical problem and, by means of a numerical parametric analysis, an equation to predict theta is developed. The equation is verified through several numerical assessments in which the parameters are modified simultaneously and arbitrarily. In addition, the qualitative influence of each nondimensional parameter on the interface shape is reported., 7 pages, 12 figures

Soft matter deforms in response to imposed external forces. Here we demonstrate how dynamic surface forces are linked to far-field deformations. This offers a new paradigm for determining forces between soft particles in colloidal systems. The particular example we use to illustrate this concept is that of a fluid drop interacting with a solid wall through hydrodynamic drainage flow coupled with repulsive or attractive dissimilar electrical double layer interactions. The force can be deduced from a simple analysis of the drop surface geometry outside the interaction zone.