Split Flow Research Articles

A comparison between fossil and synthetic kerosene flames from the perspective of soot emissions in a swirl spray RQL burner

Swirl-stabilized turbulent spray flames operating at atmospheric pressure, with both a conventional Jet-A kerosene (‘A2’) and a synthetic fuel blend (‘C5’) and radially-injected dilution air were investigated from the perspective of soot emissions in a model Rich-Quench-Lean (RQL) combustor. The primary and downstream dilution air flow split was varied while keeping the global equivalence ratio constant (ϕg=0.4). 2.5 kHz PIV, 5 kHz OH-PLIF, and simultaneous 10 Hz Mie scattering and LII were used. Results revealed a correlation between OH and soot distributions. With no dilution air, soot volume fractions (fv) peaked in a v-shaped cone between the OH-containing regions along the spray cone and those anchored to the bluff body. With dilution air at 20% of total air flow, fv shifted to the central axis as OH distributions widened. At 40% dilution, soot initiation began farther downstream along the spray cone, OH regions merged into one, and fv peaked farther downstream at the edge of the Central Recirculation Zone (CRZ). With no air dilution, peak time-averaged fv was 20% lower in the C5 flame compared to A2, despite C5 having a higher aromatics content. However, at 20% dilution fv in C5 increased by 75% compared to the no dilution case. fv in the C5 flame dropped by 12.5% in the high dilution case compared to 40% reductions in A2. Mie scattering showed that the C5 spray was shorter and more resistant to change from dilution air compared to A2. The different spray behaviours were due to C5’s flat boiling range, lower viscosity and density, leading to higher evaporation rates. Detailed chemistry laminar flamelet simulations of A2 and C5 showed that peak soot precursor species mass fraction values and temperatures decreased as the scalar dissipation increased and a significantly stronger presence of toluene in the C5 flame compared to A2. Toluene’s soot yielding behaviour may cause C5’s increased fv with moderate dilution compared to A2. C5 demonstrates the importance of the fuel’s chemical and physical properties when developing future sustainable aviation fuels for practical applications to maximize their soot mitigation potential.

Analysis of an ampoule found on a WW2 German soldier: Poison or medicine?

During archaeological excavations in Maltot, Normandy (France), the remains of a German soldier probably dating from Operation Jupiter (July 10–11, 1944) were discovered. The study of the body showed that he was a man aged 17 to 20 at the time of death. His death was likely caused by several recent projectile impacts: bullet entry orifice in the skull and several shrapnel traces in the upper limbs. Several objects were found near the body, including the remains of a leather and metal box at the level of is abdomen containing about ten glass whole ampoules while 2 others laid loose. The objective of this work was to identify the contents of these ampoules, with an emphasis on poisons. Screenings were carried out on the contents of the vial using HPLC-DAD, GC-MS, HS-GC-MS and HR-LC-MS/MS. Multi-element research by ICP-MS was also conduct as well as cyanide research. Volatile compounds quantification was performed using GC-MS equipped with a Triplus AS Head space injector (Thermo Fisher Scientific, Les Ulis, France). Chromatographic separation was achieved on a Rtx-VMS column (30 m × 0.25 mm, dF = 1.4 μm) (Restek, Lisses, France) with helium as carrier gas at a constant flow rate of 1.2 mL/min. Injector temperature was held at 65 °C and split injection mode was employed with a split flow of 80. The GC conditions were as follows: column temperature started at 40 °C, was held for 2 min then increased to 150 °C at a rate of 10 °C/min then held for 1minute. 5 μL of the sample was put in a sealed vial then heated to 80 °C during 20 minutes with a 10 second agitation step. 0.2 mL of the gas phase was injected in the GC/MS. Data acquisition was performed using the Xcalibur v2.1 software (Thermo Fisher Scientific). The detection was operated in SIM mode. Propan-1-ol was used as internal standard (E.I.). Calibrators were prepared at 50, 100, 200, 500 and 1000 mg/L in DMSO. Analyzed ampoule was 6 cm long and 0.5 cm wide and contained approximately 300 μL of a colorless, water-immiscible liquid, with a characteristic solvent odor. HPLC-DAD, GC-MS, HR-LC-MS/MS, ICP-MS and cyanide screenings were negative. However, the HS-GC-MS analysis revealed the presence of several volatile products: ethanol (360 g/L), chloroform (392 g/L), diethyl ether (87 g/L), as well as isopropanol, trichloroethylene and tetrachloroethylene at concentrations lower than 5 g/L. No poison but two anesthetic substances (chloroform and diethyl ether) associated with an alcoholic solvent (ethanol) were found. Therefore, the soldier was probably a medic. The anesthetic properties of ether were discovered in 1846 leading to a revolution in surgery and the beginnings of anesthesia. A few months later, the anesthetic properties of chloroform were uncovered. Around 1860, in England, the A.C.E. mixture which consisted of 1 part alcohol, 2 parts chloroform and 3 parts ether was preferred over chloroform alone. This mixture was later introduced in Germany where it was used until WW2 (Wawersik J. J Clin Anesth, 1991 3(3) 235–244). Composition of the analyzed vials seems to match this A.C.E. mixture and coherent with historical knowledge. These molecules were administrated by inhalation and it was often regarded as a safe and simple procedure for urgent situations as encountered on the battlefield. For more complex procedures, use of barbiturates was preferred. After WW2, A.C.E. mixture was abandoned in favor of less toxic anesthetics such as nitrous oxide.

Impact of precessing vortex core dynamics on the thermoacoustic instabilities in a swirl-stabilized combustor

Global instabilities in swirling flows can significantly alter the flame and flow dynamics of swirl-stabilized flames, such as those in modern gas turbine engines. In this study, we characterize the interaction between the precessing vortex core (PVC), which is the consequence of a global hydrodynamic instability, and thermoacoustic instabilities, which are the result of a coupling between combustor acoustics and the unsteady heat release rate. This study is performed using experimental data obtained from a model gas turbine combustor employing two concentric swirling nozzles of air, separated by a ring of fuel injectors, operating at five bar pressure. The flow split between the two streams is systematically varied to observe the impact of flow structure variation on the system dynamics at both non-reacting and reacting conditions. High-speed stereoscopic particle image velocimetry, OH planar laser-induced fluorescence and acetone planar laser-induced fluorescence are used to obtain information about the velocity fields, flame and fuel flow behaviour, respectively. Spectral proper orthogonal decomposition and a complex network analysis are used to identify and characterize the dominant oscillation mechanisms driving the system. In the non-reacting data, a PVC is present in most cases and the amplitude of the oscillation increases with increasing flow through the centre nozzle. In the reacting data, three dominant modes are seen: two thermoacoustic modes and the PVC. Our results show that in the cases where the frequency of the PVC overlaps with either of the thermoacoustic modes, the thermoacoustic modes are suppressed. The complex network analysis coupled with a weakly nonlinear theoretical analysis suggests the mechanisms by which this coupling and suppression of the thermoacoustic mode occur.

Framework for patient-specific simulation of hemodynamics in heart failure with counterpulsation support.

Despite being responsible for half of heart failure-related hospitalizations, heart failure with preserved ejection fraction (HFpEF) has limited evidence-based treatment options. Currently, a substantial clinical issue is that the disease etiology is very heterogenous with no patient-specific treatment options. Modeling can provide a framework for evaluating alternative treatment strategies. Counterpulsation strategies have the capacity to improve left ventricular diastolic filling by reducing systolic blood pressure and augmenting the diastolic pressure that drives coronary perfusion. Here, we propose a framework for testing the effectiveness of a soft robotic extra-aortic counterpulsation strategy using a patient-specific closed-loop hemodynamic lumped parameter model of a patient with HFpEF. The soft robotic device prototype was characterized experimentally in a physiologically pressurized (50–150 mmHg) soft silicone vessel and modeled as a combination of a pressure source and a capacitance. The patient-specific model was created using open-source software and validated against hemodynamics obtained by imaging of a patient (male, 87 years, HR = 60 bpm) with HFpEF. The impact of actuation timing on the flows and pressures as well as systolic function was analyzed. Good agreement between the patient-specific model and patient data was achieved with relative errors below 5% in all categories except for the diastolic aortic root pressure and the end systolic volume. The most effective reduction in systolic pressure compared to baseline (147 vs. 141 mmHg) was achieved when actuating 350 ms before systole. In this case, flow splits were preserved, and cardiac output was increased (5.17 vs. 5.34 L/min), resulting in increased blood flow to the coronaries (0.15 vs. 0.16 L/min). Both arterial elastance (0.77 vs. 0.74 mmHg/mL) and stroke work (11.8 vs. 10.6 kJ) were decreased compared to baseline, however left atrial pressure increased (11.2 vs. 11.5 mmHg). A higher actuation pressure is associated with higher systolic pressure reduction and slightly higher coronary flow. The soft robotic device prototype achieves reduced systolic pressure, reduced stroke work, slightly increased coronary perfusion, but increased left atrial pressures in HFpEF patients. In future work, the framework could include additional physiological mechanisms, a larger patient cohort with HFpEF, and testing against clinically used devices.

Nickel removal by biogenic selenium nanoparticles (SeNPs): Characterization and simulation of non-symmetric breakthrough curves in continuous-flow packed-bed columns

Nanoparticles offer an alternative mean for heavy metals removal from aquatic environment. In this work we study the sequestering of nickel by biogenic selenium nanoparticles (SeNPs) both in native and in immobilized form in alginate matrix (alginate-SeNPs). The apparent sorption like process is attributed to the coordination chemistry of Ni with the functional groups of the extracellular polymeric substances (EPS) covering the SeNPs. The kinetics and the equilibrium of the process are presented, while the morphology and the properties of the adsorption beads are studied by SEM, FTIR and rheological analysis. Langmuir isotherm describes the adsorption equilibrium with maximum loading Q0 29.411 mg Ni/g SeNPs and 0.651 mg Ni/g alginate-SeNPs. The adsorption of nickel is fast and equilibrium is attained within one hour. Continuous flow experiments in packed beds reveal early elution patterns and non-symmetric sigmoidal profiles due to the reduced adsorption capacity of the immobilized SeNPs, the short depth of the beds and the apparent non-uniform flow pattern. The Bohart-Adams equation fits adequately the main sigmoidal part of the breakthrough curves, however fails to predict the early breakthrough data. By using the advection–dispersion-reaction equation (ADR) under two novel aspects: (a) the rapid equilibrium model with the introduction of an efficiency coefficient accounting for all the kinetic and sorption limitations and (b) the split flow model accounting for any non-uniform flow conditions in the column, the model accuracy is significantly improved. Repeated sorption–desorption experiments show that alginate-SeNPs retain 59% of the original adsorption capacity even after eight cycles.

Mechanisms of Valley Precipitation Enhancement over Da-Tun Mountain

Abstract This study explores the mechanisms responsible for valley precipitation enhancement over Da-Tun Mountain under the prevailing northeasterly monsoonal flow. Da-Tun Mountain, located adjacent to the northern coast of Taiwan, is a small-scale (15 km), concave-like terrain feature with two ridge arms and a funnel-shaped valley. A typical valley precipitation enhancement event that occurred on 13 December 2018 was chosen for detailed analyses. Upstream conditions were characterized by the absence of convective available potential energy with a large-Froude-number (>1) flow regime. Observational and modeling results indicate a consistent, important signature of flow splitting due to partial blocking as the low-level northeasterly flow encountered the ridge arms. Fine-scale structures of airflow and precipitation evident from the simulations further reveal that the deflected flows over the two ridge arms interacted with each other to produce lateral convergence and enhanced precipitation inside the valley. The smaller-scale splitting flows tended to occur over the ridge arms as upstream moist Froude number decreased from relatively higher (5–11) to lower (3–5) values due to the temporal change in moist static stability. Quantitative diagnoses of vertical velocities performed over the region of primary precipitation support that upward motions associated with lateral convergence greatly overwhelmed the upslope-forced lifting over the valley region during the valley precipitation enhancement periods. However, vertical motions over the ridge arms with steeper slopes were dominantly contributed by the upslope forcing, but their intensities were also modulated by the flow-splitting-induced divergence. Significance Statement Many mountain ranges around the world exhibit a concave-like terrain feature with various spatial scales and orientations. Orographic modulations of rainfall by concave mountains are of great importance to local weather, as torrential rainfall has been frequently reported over these ridges in different geographical locations. This study aims to advance our knowledge of precipitation mechanisms over Da-Tun Mountain, a small-scale concave topography located in northern Taiwan. Observational and modeling analyses reveal evidence of splitting flows over different ridge arms of this mountain barrier. These smaller-scale splitting flows and their interactions play important roles in modulating the intensity of upslope-forced lifting and contributing to valley precipitation enhancement. These identified processes are anticipated to be commonly active over highly three-dimensional, concave-like topography.

Physico-mathematical apparatus for numerical modelling of feed expander

The productivity of the feed preparation line and its technical and economic efficiency are affected by the design and technological parameters of the equipment. The geometry of the expander screw and its operating modes are no exception. To reduce the specific energy consumption of the expander, it is necessary to establish its rational design and operating parameters. This can be done using analytical calculation methods that consider the mechanisms of movement and destruction of solid substances. Modelling using the discrete element method is becoming increasingly common to describe the movement of solid components in granulators, extruders, or expanders. The purpose of the study is to improve the physical and mathematical apparatus of movement of solid feed components in the screw channel of the feed expander and develop a method for its numerical modelling. Numerical modelling was performed using a model of the movement of a multiphase Euler mixture with a split flow in three-dimensional space. In this case, the motion was subject to an admissible two-layer k-ε model of turbulence and the multiphase equation of state. The physical and mathematical apparatus for the movement of solid feed components in the screw channel of the feed expander was improved, which is the basis for the numerical modelling technique in the Star-CCM+ software suite, based on the fact that the conglomerate of feed components is represented as a package of spherical particles. In this case, the pressure force must be compensated by the total force of contact interaction of particles with each other and the wall. Preliminary numerical modelling of the process of expanded feed preparation was performed in the Star-CCM+ software suite. The practical significance lies in the fact that the improved physical and mathematical apparatus and the developed method of numerical modelling of the feed expander operation process allow substantiating its design and regime parameters to ensure low specific energy consumption without losing the quality of the technological process

The impact of boundary treatment and turbulence model on CFD simulations of the Ranque-Hilsch vortex tube

In this work the relative impacts that different boundary conditions have on the temperature separation predictions of 3D Computational Fluid Dynamics (CFD) models of the Ranque-Hilsch Vortex Tube (RHVT) are explored. Concurrently, in the interest of comparing to experimental results, the impact of including the exit plenums and inlet shroud in the computational models of temperature separation are examined. Simulations of the 3D model using the k−ε, k−ω, k−ω SST and Scale-Adaptive-Simulation SST turbulence models are presented and their relative impacts on flow structure and energy separation are discussed. The results of this study show that imposition of the inlet mass flow combined with mass flow rate at one outlet and pressure at the other leads to reasonable predictions, whereas multiple pressure conditions at RHVT boundaries leads to errors in inlet flow or mass flow split. It is also shown that each turbulence model predicts a unique eddy viscosity distribution inside the vortex tube and that the length of the stagnation stream surface is negatively correlated to the (average) eddy viscosity. By this observation, it is noted that the integral results for energy separation are not sufficient to determine which turbulence model is best.

Comprehensive two-dimensional liquid chromatographic method (Chiral × Achiral) for the simultaneous resolution of pesticides

This work demonstrates the potential of two-dimensional liquid chromatography (2D-LC) to increase the resolution capacity of multiple pesticides in a single analysis of samples that contain both chiral and achiral compounds. The setup is based on the combination of a chiral column in the first dimension and an achiral column in the second dimension using the on-line full comprehensive mode (LC × LC). This method was optimized for the separation of 24 pesticides (17 chiral and 7 achiral). The 2D-LC system was built with an active flow splitter pump in order to easily adjust the volume of sample transferred to the second dimension and to select and optimize independently the flow rate in the first dimension. The first-dimension optimization involved the comparison of enantioresolution abilities of three different polysaccharides chiral stationary phases as well as different elution conditions, while in the second-dimension parameters like stationary phase and organic modifier were explored. Other experimental variables that influence the two-dimensional peak capacity (orthogonality, sampling frequency, shift gradients, etc.) are discussed.

Dead volume-free flow splitting in capillary electrophoresis.

In recent years, several dual detection concepts (DDCs) for CE were developed, which consisted of at least one nondestructive detector. For these DDCs, a linear detector arrangement could be used, which is not possible when both detectors are destructive. To overcome this problem, we developed a concept for the splitting of the CE stream utilizing commercially available flow splitters (FSs) that allow the parallel positioning of two destructive detectors. In this proof-of-concept study, T- and Y-shaped FSs were characterized regarding their suitability for DDCs. To keep it simple, a UV detector (UV) and a C4 D were used for the characterization. The model system consisted of an acetonitrile-based background electrolyte and the two model substances, (ferrocenylmethyl)trimethylammonium iodide and caffeine. CE hyphenated to a UV detector (CE-UV) measurements revealed that the split ratio was about 50% for both FSs. CE-C4 D was used to evaluate the peak shape in front of and behind the FSs. These measurements showed that there was no significant peak broadening introduced by the FSs. Additionally, there were no changes in the LODs in front of and behind the FSs. Furthermore, the flexibility of the new FS approach allowed the usage of capillaries with different ids (25-75µm) for injection and detection.

Computational Investigation of Anastomosis Options of a Right-Heart Pump to Patient Specific Pulmonary Arteries.

Patients with Fontan circulation have increased risk of heart failure, but are not always candidates for heart transplant, leading to the development of the subpulmonic Penn State Fontan Circulation Assist Device. The aim of this study was to use patient-specific computational fluid dynamics simulations to evaluate anastomosis options for implanting this device. Simulations were performed of the pre-surgical anatomy as well as four surgical options: a T-junction and three Y-grafts. Cases were evaluated based on several fluid-dynamic quantities. The impact of imbalanced left-right pulmonary flow distribution was also investigated. Results showed that a 12-mm Y-graft was the most energy efficient. However, an 8-mm graft showed more favorable wall shear stress distribution, indicating lower risk of thrombosis and endothelial damage. The 8-mm Y-grafts also showed a more balanced pulmonary flow split, and lower residence time, also indicating lower thrombosis risk. The relative performance of the surgical options was largely unchanged whether or not the pulmonary vascular resistance remained imbalanced post-implantation.

Dense medium separator performance evaluation based on 3D Eulerian-Eulerian multiphase CFD simulation

ABSTRACT The present paper enumerates a CFD model developed for a 76-mm Dense Medium Cyclone (DMC) using Ansys Fluent Software to gain insights into the separation of particles according to their size and density. The simulation used in this paper includes Reynolds stress model to predict the turbulence inside the cyclone body. An Eulerian–Eulerian multiphase CFD model was applied to model a number of physical aspects such as the separation of coal particles and the segregation of magnetite media solids. The experimental results generated in a laboratory-scale DMC were used for the validation purpose, and the predicted results of CFD have been validated for the flow splits of water, magnetite, and coal. The simulation results obtained from the Eulerian–Eulerian multiphase model reveal that the prediction is in good agreement with experimental results and match reasonably well in terms of the mass flow rates of water, magnetite, and coal. Furthermore, the partition curve of the DMC when mapped for the separation of −3.0 + 0.50 mm size also showed to be in agreement with the experimentally obtained curves. The gravity of cut (SG50) has also been predicted by the Eulerian–Eulerian multiphase CFD model and was found to be in the vicinity of observed experimental value of SG50.

In vitro measurement of hepatic flow distribution in Fontan vascular conduits: Towards rapid validation techniques

Fontan operation is the last stage of single-ventricle surgical reconstructions that connects superior and inferior vena cava (SVC, IVC) to the pulmonary arteries. The key design objectives in total cavopulmonary connections (TCPC) are to achieve low power loss (PL) and balanced hepatic flow distribution (HFD). Computational fluid dynamics (CFD) played a pivotal role in pre-surgical design of single-ventricle patients. However, the clinical application of current CFD techniques is limited due to their complexity, high computational time and untested accuracy for HFD prediction. This study provides a performance assessment of computationally low-cost steady Reynolds-Averaged Navier-Stokes (RANS) k-ɛ turbulent models for simulation of Fontan hemodynamics. The performance is evaluated based on prediction accuracy for three clinically important Fontan hemodynamic indices: HFD, PL and total pulmonary flow split (TPFS). For this purpose, a low-cost experimental technique is developed for rapid quantification of Fontan performance indices. Experiments and simulations are performed for both an idealized and a complex 3D reconstructed patient-specific TCPC. Time-averaged flow data from phase contrast MRI was used as the boundary conditions for the patient-specific model. For the idealized model, different SVC/IVC flow ratios corresponding to different cardiac outputs and Reynolds’ numbers were examined. This study revealed that steady RANS k-ɛ models are able to estimate the Fontan hemodynamic indices with acceptable accuracy within minutes. Among these, standard k-ɛ two-layer was found to deliver the best agreement with the in vitro data with an average error percentage of 1.7, 2.0 and, 3.9 for HFD, TPFS and, PL, respectively for all cases.

Experimental study on the separation performance of an enhanced cyclone with shunt device

To expand the application field of the cyclone, an enhanced cyclone with shunt device (ECSD) is proposed to continuously remove coarse particles from the air. To study the performance of the ECSD, an experimental bench was set up, and a series of analyses were carried out using silica particles, talc powder and light calcium powder to simulate particles in air. The effects of the split flow rate, particles (feed concentration and physical properties), feed flow rate and feed static pressure on the separation performance were investigated. The experimental results show that the separation efficiency of the ECSD is higher than that of a traditional cyclone, and continuous particle separation can be realized. With the split flow rate increasing from 0 m3/h to 5.2 m3/h, the total separation efficiency and reduced separation efficiency increase by 53% and 37%, respectively. However, the split flow rate of this model should be controlled within 5.2 m3/h (split ratio 45%); otherwise, the separation efficiency could not be effectively improved and the energy consumption would increase. The cut-off sizes for talc powder, light calcium powder and silica particle are approximately 3.6 μm, 3.8 μm and 5 μm, respectively. For particles with sizes less than 1 μm, the separation efficiency of the ECSD can still exceed 25%. Note that the ECSD has great potential to apply to the field where particulate matter needs to be removed.

Numerical Study of Oil-water Separation in Inline Axial Hydrocyclone

The fluid mixture hydrocyclone is an excellent tool for downhole oil/water separation (DOWS) for high water cut. In the present work the flow through inline axial inlet hydrocyclone is investigated computationally using ANSYS-FLUENT-19 software. The three dimensional continuity and momentum equations with SST k-omega turbulence model are used to simulate the strongly swirling, turbulent flow. Oil/water two phase mixture treated as the working fluid, water is considered as the primary phase and oil is the secondary phase. The considered oil volume fraction this work is 0.25 and flow split is 0.3 for three different flow rates of (14, 28, 56) m3/hr corresponding to Reynold's number range of (1.6 to 6.6)*104. The pressure and velocity fields were analyzed in the whole hydrocyclone with core recirculation. The results are helpful to predict the flow motion inside the cyclone to estimate the oil/water separation process. The present work indicates that the water purity at cyclone exit was 90%, while the obtained oil purity was 38%.

A combined and robust modal-split/traffic assignment model for rail and road freight transport

Searching for achieving an ambitious reduction in greenhouse gas emissions, the EU has set as a goal a modal shift in freight transport of 30% by rail for the near future. In this context, it is vital to use modal choice models road versus rail to assess the shippers’ acceptance of the actions promoting the use of rail. This paper develops a combined model for jointly evaluating modal split and railway freight flows, addressed to the case when a modal split based on a random utility model is available, and some of its coefficients may present a non-negligible variability. To this end, after the initial deterministic formulation a robust counterpart of the model is developed. The model, formulated as a non-linear integer programming problem, is oriented to a multi-carrier environment and includes constraints to consider the interactions between the different types of flows on the railway network, allowing a good evaluation of the cost types of the carriers and the network capacity. An algorithmic solution based on the outer approximation method is shown to provide accurate solutions in a reasonable computational time for the robust and non-robust versions of the model. Examples centered on a section of the Trans-European Transport Network, the TEN-T Core network corridors, are reported to test the model’s applicability. Results show that this model can be a helpful tool for analyzing the possible shippers’ response to the different railway carriers’ services competing with the road.

Inertia-Induced Breakdown of Acoustic Sorting Efficiency at High Flow Rates

The clinical utility of microfluidic techniques is often hampered by an unsatisfying sample throughput. Here, the effect of inertial forces on acoustofluidic particle sorting at high sample throughputs is investigated experimentally and theoretically. Polystyrene particles are acoustically prefocused to obtain precise trajectories. At increased flow rates it is observed that the particle stream is displaced towards the channel center, and above specific flow settings the particles spill over into the center outlet. This effect, coined the spillover effect, illustrates the complex interplay of viscous and inertial forces inside the microchannel. The effect is due to increased bending of the separatrices at the inlet and outlets and not due to the wall-lift force. The impact of the spillover effect on the separation of two different-sized particles is subsequently studied. Efficient sorting is done for subcritical splitting ratios and flow rates, but for close to critical settings or beyond, there is a breakdown of the acoustofluidic separation.

An experimental study on bidirectional pedestrian flow involving individuals with simulated disabilities in a corridor

Individuals with disabilities are essential members of heterogeneous crowds. However, empirical data on pedestrian flow, including individuals with disabilities, are limited. In this study, a controlled experiment was conducted to explore the dynamics of counterflow involving individuals without disabilities and with simulated disabilities. For safety reasons, some individuals without disabilities were recruited to simulate persons with mobility-related physical and sensory disabilities (namely pedestrians on crutches, seniors, wheelchair users and persons who are blind) by using auxiliary equipment. A total of 64 pedestrians participated in the experiment. After gaining their movement trajectories, crossing behaviors, spatial–temporal characteristics, fundamental diagrams and the congestion level are analyzed under different split flow ratios of walkers from two directions and densities. Results demonstrate that the average speed of pedestrians in the direction of pedestrian flow comprising more participants is higher than that in the other direction. Helping behavior positively impacts on the movement efficiency of heterogeneous crowds, while the proportion of individuals with simulated disabilities has a negative impact. The split flow ratio has little effect on the average specific flow when density is smaller than approximately 1.25 m−2. The average specific flow in balanced flow (i.e. the split flow ratio is 0.5) is slightly higher than that in unbalanced flow (i.e. the split flow ratio is not 0.5) when density is larger than approximately 1.25 m−2. Congestion level is relatively higher here than that in counterflow, including all individuals without disabilities, when density is low. These findings have implications for safer pedestrian facility design.

Computational study of a novel catheter for liver radioembolization.

Radioembolization (RE) is a medical treatment for primary and secondary liver cancer that involves the transcatheter intraarterial delivery of micron‐sized and radiation‐emitting microspheres, with the goal of improving microsphere deposition in the tumoral bed while sparing healthy tissue. An increasing number of in vitro and in silico studies on RE in the literature suggest that the particle injection velocity, spatial location of the catheter tip and catheter type are important parameters in particle distribution. The present in silico study assesses the performance of a novel catheter design that promotes particle dispersion near the injection point, with the goal of generating a particle distribution that mimics the flow split to facilitate tumour targeting. The design is based on two factors: the direction and the velocity at which particles are released from the catheter. A series of simulations was performed with the catheter inserted at an idealised hepatic artery tree with physiologically realistic boundary conditions. Two longitudinal microcatheter positions in the first generation of the tree were studied by analysing the performance of the catheter in terms of the outlet‐to‐outlet particle distribution and split flow matching. The results show that the catheter with the best performance is one with side holes on the catheter wall and a closed frontal tip. This catheter promotes a flow‐split‐matching particle distribution, which improves as the injection crossflow increases.

Impact of Advance Payments of Tax on Profit on Effectiveness of Investments

Recently Brusov et al. have developed innovative investment models that are very close to investment practice. Investment models with frequent payments of tax on profit and of interest on debt at the ends of periods have been considered. However, in practice, payments of tax on profit as well as of interest on debt could be made in advance. In the current paper, we developed, for the first time, innovative investment models with frequent advance payments of tax on profit and of interest on debt and studied the impact of these types of payments on investment project effectiveness. Numerical calculations carried out for four innovative investment models (without split flows) showed that, in the case of advance frequent payments of income tax and interest on debt, all the results related to the effect of the number of payments of income tax and interest on debt on the investment projects’ effectiveness were opposite to the results in the case of payments at the end of the periods obtained by Brusov et al. in the previous article. Thus, this means that the method of payments of tax on profit and of interest on debt (in advance or at the ends of periods) changes drastically the effect of the number of payments of income tax and interest on debt on the investment effectiveness. The verification developed by us for the new models with frequent advance payments of tax on income helps create a comprehensive system of correct valuation of the investments’ effectiveness for two schemes for payments of income tax (in advance or at the ends of periods). The obtained results help the tax regulator (Finance Ministry) understand the influence of the frequency of payments of tax on income and the credit regulator (Central Bank) understand the influence of the frequency of payments of interest on debt on the investment projects’ effectiveness. This allows them to modify and improve tax legislation and credit policy, respectively.