Narrow Cross Research Articles

Interaction of inertia and magnetic force in the liquid metal flow past a magnetic obstacle

In this paper, we present a numerical study of the three-dimensional behavior of a liquid metal flow in an insulating rectangular duct of narrow cross section past a localized magnetic field (i.e., a magnetic obstacle) produced by two parallel square magnets arranged externally on the walls of the duct. A series of simulations are conducted focused mainly on describing the interplay between inertial and magnetic forces in a wide range of interaction parameters (1.8<N<48) by varying the Reynolds number while the Hartmann number is kept fixed (Ha = 75). The analyzed configuration coincides with that studied experimentally by Domínguez et al. [“Experimental and theoretical study of the dynamics of wakes generated by magnetic obstacles,” Magnetohydrodynamics 51(2), 215–224 (2015)] and, as a first step, experimental data from local variables (streamwise velocity component) and global parameters (oscillation frequency and kinetic energy of the wake) are consistently replicated by the numerical model. Furthermore, to complement the flow phenomenology, the transition to different flow structures as the interaction parameter varies is explored. It is found that when the magnetic forces predominate over inertia, stationary vortex patterns with two, four, and six vortices appear while, unlike the hydrodynamic flow past a bluff body, the increase in inertial effects leads to a reduction in the number of vortices and eventually to their disappearance, reaching a state in which the magnetic obstacle becomes imperceptible to the flow. The existence of a critical value of the interaction parameter that maximizes the kinetic energy of the wake is confirmed numerically and corroborated from the experimental data.

Lateral buckling of the compressed edge of a beam under finite bending

This paper investigates the critical condition whereby the compressed edge of a beam subjected to large bending exhibits a sudden lateral heeling. This instability phenomenon occurs through a mechanism different from that usually studied in linear theory and known as flexural–torsional buckling. An experimental test device was specifically designed and built to perform pure bending tests on soft materials. Thus, the experimental campaign provides not only the moment-curvature behavior of beams of narrow rectangular cross section, but also information regarding the post-critical lateral buckling behavior. To study the local bifurcation phenomenon, an analytical model is proposed in which a field of small transversal displacements, typical of the linear stability of thin plates, is superimposed on the large vertical displacement field of an inflexed beam in the nonlinear elasticity theory. Furthermore, numerous numerical simulations through nonlinear FE analysis have been performed. Finally, the results provided by the different methods applied were compared and discussed.

The Design and Location Characteristics of Wildlife Overpasses in Hungary

Hungary's motorway network has developed significantly over the past twenty years. These developments have increased the length of fenced roads, which also means increased habitat fragmentation effects. Wildlife crossings have been built on new sections to reduce isolation caused by roads. This study examined 57 wildlife overpasses using satellite imagery. We determined the internal and overall widths of the crossings, their total length and the length of the noise barriers, as well as the width-to-length ratio. The crossings were classified according to ramp design, noise barrier material and noise barrier run-down. In addition, a surface cover map was used to examine landscape features within 500 m of the crossings and evaluate the crossings' placement. Our results show that the average width of the overpass corridor was 14.4 m. The width-to-length ratio was 0.16. Based on this, we concluded that the wildlife crossings in Hungary could be classified as narrow crossings. There was also considerable variation in design characteristics, with the crossings studied not being uniform in either ramp design or noise barrier characteristics. The results of the placement's landscape characterisation indicate that many overpasses in agricultural areas are particularly favourable for roe deer (Capreolus capreolus).

Simple method for determining asymptotic states of fast neutrino-flavor conversion

Neutrino-neutrino forward scatterings potentially induce collective neutrino oscillation in dense neutrino gases in astrophysical sites such as core-collapse supernovae (CCSN) and binary neutron star mergers (BNSM). In this paper, we present a detailed study of fast neutrino-flavor conversion (FFC), paying special attention to asymptotic states, by linear stability analysis and local simulations with a periodic boundary condition. We find that asymptotic states can be characterized by two key properties of FFC: (1) the conservation of lepton number for each flavor of neutrinos and (2) the disappearance of ELN(electron neutrino-lepton number)-XLN(heavy-leptonic one) angular crossings in the spatial- or time-averaged distributions. The system which initially has the positive (negative) ELN-XLN density reaches a flavor equipartition in the negative (positive) ELN-XLN angular directions, and the other part compensates it to preserve the conservation laws. These properties of FFCs offer an approximate scheme determining the survival probability of neutrinos in asymptotic states without solving quantum kinetic equations. We also demonstrate that the total amount of flavor conversion can vary with species-dependent neutrino distributions for identical ELN-XLN ones. Our results suggest that even shallow or narrow ELN angular crossings have the ability to drive large flavor conversion, exhibiting the need for including the effects of FFCs in the modeling of CCSN and BNSM.

Across-track extension of retrieved cloud and aerosol properties for the EarthCARE mission: the ACMB-3D product

Abstract. The narrow cross section of cloud and aerosol properties retrieved by L2 algorithms that operate on data from EarthCARE's nadir-pointing sensors is broadened across-track by an algorithm that is described and demonstrated here. This scene construction algorithm (SCA) consists of four components. At its core is a radiance-matching procedure that works with measurements made by EarthCARE's Multi-Spectral Imager (MSI). In essence, an off-nadir pixel gets filled with retrieved profiles that are associated with a (nearby) nadir pixel whose MSI radiances best match those of the off-nadir pixel. The SCA constructs a 3D array of cloud and aerosol (and surface) properties for entire frames that measure ∼6000 km along-track by 150 km across-track (i.e., the MSI's full swath). Constructed domains out to ∼15 km across-track on both sides of nadir are used explicitly downstream as input for 3D radiative transfer models that predict top-of-atmosphere (TOA) broadband solar and thermal fluxes and radiances. These quantities are compared to commensurate measurements made by EarthCARE's Broadband Radiometer (BBR), thus facilitating a continuous closure assessment of the retrievals. Three 6000 km ×200 km frames of synthetic EarthCARE observations were used to demonstrate the SCA. The main conclusion is that errors in modelled TOA fluxes that stem from use of 3D domains produced by the SCA are expected to be less than ±5 W m−2 and rarely larger than ±10 W m−2. As such, the SCA, as purveyor of information needed to run 3D radiative transfer models, should help more than hinder the radiative closure assessment of EarthCARE's L2 retrievals.

Thermal characteristics of refrigerant flow boiling in two mini-channel heat sinks of different aspect ratios for battery thermal management

The two-phase refrigerant cooling system has excellent thermal management performance, which can provide good temperature control of lithium-ion batteries. In this paper, the thermal performance of mini-channel heat sinks with different aspect ratios was investigated for a battery module with a small-scale vapor compression refrigeration system. Two mini-channel heat sinks (MiCHSs), one with a narrow channel cross section of 2 mm × 4.5 mm (MiCHS1) and the other one with square channel cross section of 3 mm × 3 mm (MiCHS2), were fabricated with a visualization window and connected in parallel in the system. The experiments were run at different openings of expansion valve (OEV) and heating power. With the increase of OEV, the refrigerant subjected to fixed heating power in the mini-channels experiences different flow patterns of annular flow, slug flow and small-bubble flow successively. The best cooling performance can be achieved in slug flow, corresponding to an optimal OEV. The optimal OEV value increased from 32 % to 55 % with the increase of heating power ranging from 100 W to 200 W. Under the same optimal OEV condition, the heat transfer coefficient and average temperature of MiCHSs increase with the increase of heating power for both MiCHSs. The channel aspect ratio has an effect on the heat transfer performance of MiCHS. Compared with the narrow channels of MiCHS 1 with a large aspect ratio, the flow boiling in square channel of MiCHS2 can achieve a better cooling performance due to the well-confined bubbly flow and thinner liquid film on the base of the mini-channels.

PROCESS AUTOMATION OF WAREHOUSE INSPECTION USING AN AUTONOMOUS UNMANNED AERIAL VEHICLE

Inventory management applications using unmanned aerial vehicles (UAVs) appear to have the highest potential for use in warehouse operations. They remove the need for manual inspection, which is in most cases performed in heights using ladder, pen and paper. Moreover, it provides a competitive edge in the field of logistics while decreasing costs and improving stock management efficiency. Deployment of autonomous UAVs in an indoor environment puts higher requirements for the level of autonomy due to the more complex nature of the environment (narrow crossings, absence of Global Navigation Satellite System (GNSS), smaller manoeuvring space, dynamic environment, etc. ...). In this paper, we would like to introduce a system for automation of planning, managing, and executing a warehouse inspection. The goal is to provide an easy-to-use framework of the inspection task that any warehouse operator is capable of using it. The system consists of two main parts - user interface and path planner. Using a created human-machine interface (HMI), an operator is able to define the workspace and the inspection task. The path planning module takes as an input the definition of the inspection task defined by the operator and plans an optimised collision-less path. The operator can visualise the generated mission, launch it, observe the mission execution progress in real time and receive the mission results. The functionality of the system is verified by a simulation as well as by test flights made in an environment simulating a warehouse by a real UAV called AV Discovery built by Airvolute s.r.o.

Influence of uranium dioxide and reflector surface on neutron yields of the nuclear hybrid fusion-fission reaction using MCUNED code

The goal of the present work is to demonstrate the effects of adding uranium dioxide (UO2) to deuterium fuel in the fusion-fission hybrid reactions. The effectiveness of applying a reflector surface on the neutron yield in D-D and D-UO2 reactions has been investigated. The neutrons yielded from the fusion reactions were considered as a neutron source for fission reactions. For this purpose, MCNPX and its extension, the MCUNED code, for D-D fusion processes and UO2 fission reactions were used to calculate the neutron yield and the generated power. Using externally evaluated nuclear data libraries, MCUNED is capable of light ion transport. The D (d), (n) 3He reaction with 0.25 gm of deuterium and the fission reactions with 0.25 and 1.0 gm of UO2 were utilized. The results showed that the calculated neutron flux from the D-D fusion reaction increased by a considerable amount when applying the reflector surface. Adding 1.0 gm of UO2 to deuterium fuel enhanced neutron flux by 4.95 times on average, outside the source with the reflector surface. The calculated power increased by about 3-folds when 1.0 gm of UO2 was added. Despite the narrow cross section of the D-D reactions used in this study, it was found that utilizing the reflector surface and UO2 or depleted uranium with restrictive high masses may be able to multiply the generated neutrons and the resulting power.

PIV-based experiments on density-induced flow in an estuarine navigation channel constricted by a groin

Density-induced flow caused by horizontal salinity gradients is an important factor affecting sediment transport in estuarine navigation channels. Groins are common engineering structures that are often used to regulate and narrow these channels. In this study, PIV based laboratory experiments were conducted to investigate the effects of the groin on density-induced flow in an estuarine navigation channel. Flow fields and turbulence characteristics of the density-induced currents were investigated for various horizontal salinity gradients and different lengths of groins. PIV observations clearly show vertically stratified density currents caused by salinity gradient. Results show that groins modify the velocity field in the channel, and density currents spread horizontally after passing through channel cross sections constricted by groins. PIV experimental analyses show that, in the narrow channel cross section, the average horizontal velocity is almost unchanged under different lengths of groins if the horizontal salinity-gradient force remains the same. Results also show that the density-induced flowrate reduces after the channel is narrowed by the groin. This indicates that groins can be used to reduce the density-induced flowrate and hence reduce sediment transport along with flow in an estuarine navigation channel.

Nonsymmorphic symmetry-protected band crossings in a square-net metal PtPb4

Topological semimetals with symmetry-protected band crossings have emerged as a rich landscape to explore intriguing electronic phenomena. Nonsymmorphic symmetries in particular have been shown to play an important role in protecting the crossings along a line (rather than a point) in momentum space. Here we report experimental and theoretical evidence for Dirac nodal line crossings along the Brillouin zone boundaries in PtPb4, arising from the nonsymmorphic symmetry of its crystal structure. Interestingly, while the nodal lines would remain gapless in the absence of spin–orbit coupling (SOC), the SOC, in this case, plays a detrimental role to topology by lifting the band degeneracy everywhere except at a set of isolated points. Nevertheless, the nodal line is observed to have a bandwidth much smaller than that found in density functional theory (DFT). Our findings reveal PtPb4 to be a material system with narrow crossings approximately protected by nonsymmorphic crystalline symmetries.

A process optimization of additive layer manufacturing processes for the production of polymer composite-based components

The way additive layer manufacturing works is that materials are added in layers to create components. Every layer represents a narrow cross section of the component generated from the CAD data file. Each layer in ALM must have a defined part thickness, and the final part will be an estimate of the actual data. The last element will be the thinner surface of each layer that is formed. Modern and sophisticated ALM machines operate on a layer-based philosophy and methodology, which differs from traditional processes in terms of the materials utilised in component manufacture, the final layers formed, and how the layers are bonded to one another. These margins will look at things like the end part's correctness, as well as its material and mechanical qualities. We will determine several criteria in this study, such as how quickly the part can be manufactured utilising various ALM procedures. We also explore the beginnings of additive layer manufacturing and introduce the basic notion of additive layer manufacturing in this work. It will also go over the design process for additive layer manufacturing as well as the whole production of polymer composite based components tools. For functional engineering environments, polymer material is commonly employed to create hard and robust plastic parts. This material is extremely long-lasting, and it can be made or even welded if necessary. A minor change in the characteristics of the same material can make a big difference. ALM can be helpful at this point since it allows the designer to create a tangible model of the product to show its use and functions.

Numerical Study of Joule Heating Effects on Microfluidics Device Reliability in Electrode Based Devices.

In electrode-based microfluidic devices, micro channels having narrow cross sections generate undesirable temperature inside the microfluidic device causing strong thermal distribution (joule heating) that eventually leads to device damage or cell loss. In this work, we investigate the effects of joule heating due to different electrode configuration and found that, electrodes with triangular arrangements produce less heating effect even at applied potential of 30 V, without compromising the performance of the device and separation efficiency. However, certain electrode materials have low thermal gradients but erode the channel quickly thereby affecting the reliability of the device. Our simulation also predicts optimal medium conductivity (10 mS/m with 10 V) for cells to survive inside the channel until they are selectively isolated into the collection outlet. Our investigations will aid the researchers in the designing of efficient and reliable microfluidic devices to overcome joule heating inside the microchannels.

Effect of Discrete Ribs on Heat Transfer and Friction Inside Narrow Rectangular Cross Section Cooling Passage of Gas Turbine Blade

The performance of a gas turbine during the service life can be enhanced by cooling the turbine blades efficiently. The objective of this study is to achieve high thermohydraulic performance (THP) inside a cooling passage of a turbine blade having aspect ratio (AR) 1:5 by using discrete W and V-shaped ribs. Hydraulic diameter (Dh) of the cooling passage is 50 mm. Ribs are positioned facing downstream with angle-of-attack (α) of 30° and 45° for discrete W-ribs and discerte V-ribs respectively. The rib profiles with rib height to hydraulic diameter ratio (e/Dh) or blockage ratio 0.06 and pitch (P) 36 mm are tested for Reynolds number (Re) range 30000-75000. Analysis reveals that, area averaged Nusselt numbers of the rib profiles are comparable, with maximum difference of 6% at Re 30000, which is within the limits of uncertainty. Variation of local heat transfer coefficients along the stream exhibited a saw tooth profile, with discrete W-ribs exhibiting higher variations. Along spanwise direction, discrete V-ribs showed larger variations. Maximum variation in local heat transfer coefficients is estimated to be 25%. For experimented Re range, friction loss for discrete W-ribs is higher than discrete-V ribs. Rib profiles exhibited superior heat transfer capabilities. The best Nu/Nuo achieved for discrete Vribs is 3.4 and discrete W-ribs is 3.6. In view of superior heat transfer capabilities, ribs can be deployed in cooling passages near the leading edge, where the temperatures are very high. The best THPo achieved is 3.2 for discrete V-ribs and 3 for discrete W-ribs at Re 30000. The ribs can also enhance the power-toweight ratio as they can produce high thermohydraulic performances for low blockage ratios.

Effects of Vegetation, Sediment Supply and Sea Level Rise on the Morphodynamic Evolution of Tidal Channels

AbstractTidal channels play a leading role in the morphodynamic evolution of tidal environments by driving the exchange of water, sediments, and nutrients within these systems. Despite their fundamental function on landscape construction, current knowledge on their plano‐altimetric evolution in response to environmental forcing is still limited. We developed a mathematical model to address the interplay of biogeomorphic processes on the plano‐altimetric equilibrium of a straight tidal channel flanked by adjacent intertidal platforms. The model couples a one‐dimensional hydrodynamic model with a bed evolution model. The former describes the flow field within the channel and the storage contribution of lateral shoals. The latter accounts for the main physical processes responsible for shaping the tidal landscape, namely erosion, deposition, and sea level rise, mediated by halophytic vegetation growth. Model results reproduce a variety of channel morphologies, ranging from those typical of tidal‐flat channels, with large width‐to‐depth ratios, to those characterizing salt‐marsh creeks, which have much narrower cross sections and small width‐to‐depth ratios. Our results show that vegetation encroachment on the marsh surface produces two competing effects. First, vegetation increases flow concentration within the channel, owing to the increased flow resistance on the vegetated platform thus favoring channel incision. Second, vegetation promotes a reduction in the tidal prism, owing to higher accretion rates of the salt‐marsh surface thus leading to channel infilling. Which effect prevails over the other depends on the elevation of the intertidal platform in the tidal frame. The latter is in turn dictated by sediment availability, the rate of relative sea level rise, and vegetation biogeomorphic effects.

ANALISIS DAMPAK NORMALISASI SUNGAI TERHADAP EROSI DAN SEDIMENTASI DI DAERAH PERKOTAAN STUDI KASUS: SUNGAI PESANGGRAHAN, JAKARTA

Flooding is one of the problems that often occurs in the DKI Jakarta area, which one of the causes is the change of land use in watersheds that were originally into development areas. Whereas, its often the cross section of the river will be disrupted due to the loss of the riverbanks and the narrower cross section of the river. In order to overcome this, the Jakarta Provincial Government in 2013 normalized several rivers that crossed the DKI Province and one of them was the Pesanggrahan River which will be further investigated. The purpose of this study is to analyze the effect of river normalization on erosion and sedimentation which will result in changes in the longitudinal and cross section of the river. To get an accurate map of theWatershed Area, Arc-GIS software is used while identification of river flow before and after normalization was carried out based on data from Central Office of River Region Ciliwung-Cisadane, Ministry of Public Works. Sediment samples were taken at 3 points on the river, upstream, middle and downstream, that were reviewed to determine the gradation of the sediment grains. The HEC-RAS application is used to simulate sediment transport on the river section before and after normalization. The simulation results are used to determine the cross section changes due to erosion and sedimentation and to determine the water level in the river. From the water level, the hydraulic radius can be calculated and then carried out sediment transport calculation using Ackers-White equation since the equation using grain distribution from range 0.02 – 4.94 mm. The results it was found that the sediment transport in the upstream point increased 155.11 tons / year,at the midpoint increased 89.64 tons / year and the downstream point decreased 0.28 tons / year.

High spontaneous male-fertility-restorer frequency in a maize recurrent selection experiment

Using the crosses of the DH lines derived from a single cross hybrid Xianyu 335 as source materials for haploid induction in the recurrent selection scheme, we found that the rate of spontaneous chromosome doubling in the tassels of the haploid plants increased significantly in the second cycle and showed a cumulative genetic effect, and through using DH recurrent selection technique, the doubling rate of the haploid tassels can be doubled. Proved performing continuous recurrent selection in a narrow single cross background, the genetic makeup of the haploids had been enriched for spontaneous doubling restoration. Using hybrids between DH lines from two cycles haploid selection as source materials for haploid induction, the haploid tassel doubling rate had reached 85.15% and haploid ears showed seed set had reached 66.18%, representing a rate increase of 6.99 folds and 9.86 folds of its original source population Xianyu335.The genetic gain of set seeds plant frequency is 29.74% per cycle. Also, because the DH lines had been selected from two cycles of haploids or whole genome gamete selection based on the haploid phenotypes, it was effectively eliminated many deleterious and bad genes, and also cumulatively combined many superior genes for agronomy and plant growth vigor. These new DHs can be directly used as parents for germplasm enhancement and new hybrid selection and breeding. The discovery of the enrichment for spontaneous chromosome doubling and fertility restoration in of the tassels of the haploid plants tassels that were derived from DH recurrent selection technique and create high spontaneous doubling rate source materials may have showed a significant application value in maize breeding. It shows significant advantages for construct maize two cycle. Recurrent selection with high haploid spontaneous doubling rate can to speed up breeding output and cumulative genetic improvements.

Active Temporal Control of Radiative Heat Transfer with Graphene Nanodisks

The ability to dynamically control the radiative transfer of heat at the nanoscale holds the key to the development of a diverse number of technologies, ranging from nanoscale thermal-management systems to improved thermophotovoltaic devices. Recently, graphene has emerged as an ideal material to achieve this goal, since it can be electrically doped to support surface plasmons, collective oscillations of the conduction electrons. These resonances produce large and spectrally narrow optical cross sections, which dictate the emission and absorption properties of the graphene nanostructure and, thus, the heat that it radiatively exchanges with other objects and the environment. For attainable levels of doping, the plasmons supported by graphene nanostructures naturally lie in the midinfrared part of the spectrum, which is the most relevant wavelength range for radiative heat transfer under realistic temperatures. Furthermore, these resonances are actively tunable, thus providing full dynamic control over the heat transfer. Motivated by this great potential, we present a comprehensive analysis of the temporal evolution of the radiative heat transfer between arrangements of graphene nanodisks, showing that it is possible to exploit the tunability of these structures to obtain actively controlled heat transfer scenarios not possible with conventional passive nanostructures. The results of this work provide a framework for achieving fully dynamical control over nanoscale radiative heat transfer and thus provide fundamental insights into this process.

Computed tomography-based bronchial tree three-dimensional reconstruction and airway resistance evaluation in adolescent idiopathic scoliosis.

To investigate airway development and airway resistance by computed tomographic three-dimensional (3D) reconstruction of the bronchial tree in patients with adolescent idiopathic scoliosis (AIS). We evaluated factors predicting postoperative respiratory complications to provide timely treatment, prevent complications, and improve operative and anesthetic safety. From August 2015 to August 2017, 53 AIS patients with a mean age of 15.4years (range 10-20years) were included in this study. Scoliotic parameters on radiographs were analyzed. Airway resistance was obtained by pulmonary function testing. All patients' pulmonary bronchial trees were 3D-reconstructed via chest thin layer computed tomography to explore the correlation between the spinal-thoracic deformity parameters and airway resistance. Correlations between scoliotic parameters and airway development parameters were not statistically significant (P > 0.05). The scoliotic parameters such as Cobb angle, apical vertebral translation, rotation angle to sagittal plane, rotation angle to middle line, and apical vertebral body-rib ratio (AVB-R) were positively correlated with tracheal bifurcation angle (R2: 0.429, 0.374, 0.430, 0.504, and 0.414, respectively; P < 0.05). Cobb angle, rib hump, and apical vertebral body-rib ratio (AVB-R) were positively correlated with left principal bronchus length to right principal bronchus length (PBL-R) (R2: 0.373, 0.503, and 0.377, respectively; P < 0.05). Superficial area of bronchial tree (SABT) and narrow cross section of trachea (NCT) were negatively correlated with plethysmography Pre-Ref resistance ratio (Pre/Ref) (R2: - 0.365 and - 0.452, respectively; P < 0.05). SABT and NCT were negatively correlated with respiratory impedance (Zrs) (R2: - 0.327 and - 0.436, respectively; P < 0.05). Pulmonary bronchial development in patients with AIS is affected by spinal-thoracic deformity. Comprehensive assessment of preoperative pulmonary function, especially airway resistance, is necessary in patients with AIS whether the thoracic scoliosis is severe or mild-to-moderate. These slides can be retrieved under Electronic Supplementary Material.

Mathematical Modeling of Fluid Flow through Channels behind Well Casing

Oil and gas leakage through channels in the annular space of oil and gas wells has long been a problem responsible for sustained casing pressure and environmental issues. This type of channels forms due to low efficiency of cement placement during well cementing processes, gravity segregation after cementing horizontal wells, formation fluid invasion during the setting of cement slurry, and corrosion of formation gas, such as CO 2 and H 2 S over the life of well service. Successful sealing of the channels requires a rigorous hydraulics model for simulating the friction of sealants in the channel. The challenge is from the irregular shape of cross sections of the channels. Owing to the nature of circular shapes of wellbore and casing, bow-shape cross sections are assumed to represent these irregular shapes of cross sections. An analytical model is presented to describe laminar flow in channels of bow-shaped cross sections. The model is validated by a comparison with a traditional rectangular slot model for narrow cross sections. Result of model analysis indicates that use of rectangular cross sections to approximate bow-shaped cross sections will under-estimate the pressure gradient in narrow cross sections and over-estimate the pressure gradient in wide cross sections. A case analysis of a cement squeezing operation shows that the newly developed hydraulics model for fluid flow in channels of bow-shaped cross sections is easy to use in engineering applications.

Three-body interaction near a narrow two-body zero crossing

We calculate the effective three-body force for bosons interacting with each other by a two-body potential tuned to a narrow zero crossing in any dimension. We use the standard two-channel model parametrized by the background atom-atom interaction strength, the amplitude of the open-channel to closed-channel coupling, and the atom-dimer interaction strength. The three-body force originates from the atom-dimer interaction, but it can be dramatically enhanced for narrow crossings, i.e., for small atom-dimer conversion amplitudes. This effect can be used to stabilize quasi-two-dimensional dipolar atoms and molecules.