Hydrodynamic Flow Research Articles

Analysis of scale effect on the propulsion discrepancy of a four-waterjet system

This paper focuses on the scale effect on the propulsion discrepancy and the correlating flow characteristics of a high-speed ship with four waterjets. The propulsion discrepancy of a four-waterjet-propelled ship in model test is observed in previous study (Gong et al. Ocean Eng. 2019, 180, 211–222). Current study further performs a systematic analysis of the scale effect on several hydrodynamic coefficients (net thrust, lateral/vertical forces and torque) and flow field details (velocity, TKE and pressure). It is noted that the net thrust discrepancies are amplified in model-scale simulations and tests due to the scale effect, and the lateral/vertical force discrepancies of waterjet units are gradually decreasing with the increase of advanced speed in both scales. Stable hydraulic performance of the inner and outer pumps is observed although there are minor differences in the inflow quality, while stronger turbulence intensity exists near the channel faces in full scale due to the induction effect of the impeller.

Numerical simulation and design optimization of a circulating water channel on hydrodynamic flow performance

Numerical simulation and design optimization of a circulating water channel on hydrodynamic flow performance

A numerical scale-up study of annular fluidized bed reactor with high centrifugal acceleration

A rotating fluidized bed imposes a strong centrifugal force to form the dense annular bed with high interphase slip velocity for significantly enhanced gas-solids contact. The fundamental fluidization behaviors in rotating fluidized beds have been well understood in small-scale systems. The current study focuses on the scale-up of a rotating fluidized bed from lab-scale to commercial-scale through computational fluid dynamics modeling. The computational model was first validated against a lab-scale horizontal rotating fluidized bed for the general flow behavior and pressure drop. The validated computational model with a column diameter of 0.12 m was then scaled up to 0.48 m and 1.92 m to investigate the flow hydrodynamics at larger scales. By comparing the solids distribution and other flow field variables, major limitations in the stable operation of a rotating fluidized bed at large scales were identified. The challenges faced in the scale-up of an annular fluidized bed with centrifugal acceleration are discussed and ways to overcome such challenges are explored.

Preparation and In Vitro Characterization of Lactococcus lactis-Loaded Alginate Particles as a Promising Delivery Tool for Periodontal Probiotic Therapy.

Probiotic microorganisms are used in a variety of food supplements and medical formulations to promote human health. In periodontal therapy, probiotics are mainly used in the form of gels, tablets or rinses that often tend to leak from the periodontal pocket, resulting in a strongly reduced therapeutic effect. In this pilot in vitro study, we present biodegradable alginate-based particles as an alternative, highly efficient system for a periodontal delivery of probiotic bacteria to the inflammation site. For this purpose, Lactococcus (L.) lactis was encapsulated using a standardized pump-controlled extrusion-dripping method. Time-dependent bacterial release in artificial saliva was investigated over 9 days. The effect of freeze drying was explored to ensure long-term storage of L. lactis-loaded particles. Additionally, the particles were bound to dentin surface using approved bioadhesives and subjected to shear stress in a hydrodynamic flow chamber that mimics the oral cavity in vitro. Thus, round particles within the range of 0.80-1.75 mm in radius could be produced, whereby the diameter of the dripping tip had the most significant impact on the size. Although both small and large particles demonstrated a similar release trend of L. lactis, the release rate was significantly higher in the former. Following lyophilization, particles could restore their original shape within 4 h in artificial saliva; thereby, the bacterial viability was not affected. The attachment strength to dentin intensified by an adhesive could resist forces between 10 and 25 N/m2. Full degradation of the particles was observed after 20 days in artificial saliva. Therefore, alginate particles display a valuable probiotic carrier for periodontal applications that have several crucial advantages over existing preparations: a highly stable form, prolonged continuous release of therapeutic bacteria, precise manufacturing according to required dimensions at the application site, strong attachment to the tooth with low risk of dislocation, high biocompatibility and biodegradability.

Computational Study on Influence Factors and Vortical Structures in Static Drift Tests

This paper conducted a computational study on the KCS benchmark model at static drift conditions. At the first instance, the roles played by the grid size, turbulence model, and time step are qualitatively and quantitatively analyzed with the orthogonal experimental method (OEM). After the verification of simulated results compared with experimental data in a Static Oblique Towing Test (OTT), hydrodynamic performance is obtained with the employment of the SST κ-ω turbulence model. The grid size is set as 0.07 m while the time step as 0.01 s. The characteristics of the wake field are illustrated in different forms, such as contours of the free surface, distribution of pressure and hydrodynamic forces, variation of turbulent kinetic energy (TKE), and so on. For a deep insight into the physical mechanisms of the asymmetrical flow field, the Detached Eddy Simulation (DES) method is also utilized to capture vortical structures occurring around the hull, in comparison with results obtained through the Reynolds Averaged Navier Stokes (RANS) model. With the aim of a hydrodynamic derivative estimation or detailed flow characteristics analysis, corresponding selections of the computational method are disparate.

Investigation on the turbulent structures in combined wave-current boundary layers

The problem of turbulent vortices and vortex dynamics under the influence of ocean waves is a subject of continuing research in the field of wave-current interaction. Thus, this study investigates the evolution of turbulence structures and vortex interactions in combined wave-current boundary layers, where water waves propagate with currents. Experiments were performed in two glass-walled laboratory channels with water depths of 160 and 400 mm. A two-dimensional two-component (2D2C) Particle Image Velocimetry (PIV) system was used to measure the velocities. Periodic variations in turbulence are observed for combined wave-current flows. Pairs of counter-rotating vortices are identified in the outer region when the combined flow is reversed, leading to destructive vortex interactions. This process leads to a reduction in the turbulent kinetic energy (TKE) and TKE production and dissipation during the passage of the wave trough. A conceptual model of hairpin vortices in combined wave-current flows is proposed in this study. The results of this study provide novel insights into the hydrodynamics of combined wave-current flows.

Swimming behaviour of downstream migrating carp in accelerating flows

The downstream migration of fish is impacted by accelerating flow. This study coupled computational fluid dynamics (CFD) modelling and laboratory observations to investigate the effects of two different accelerating flow hydrodynamics on the swimming behaviours of two fish species. The silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) were chosen as target fish species and four hydrodynamic parameters were selected as main indicators to affect fish swimming behaviours. Four specific swimming behaviours were classified in the contraction flume based on fish downstream trajectories. The results indicated that high accelerating flow, low turbulent kinetic energy (Tke ) and shear stress generated the symmetric distribution of fish along two boundaries of the contraction flume. It also indicated that discharge increase would increase the fish entrainment risk from intakes to diversion pipe, while two fish species exhibited different swimming behaviour patterns. Velocity and velocity gradient had more significant effects than other hydrodynamic parameters on fish swimming strategies. There was mutual compensation among fish tail-beat frequency, angle and amplitude. The results illustrated the relationship between the swimming behaviours and hydrodynamics, which could contribute to understanding the fish downstream migration behaviours in accelerating flow.

Piston problem for the pressureless hydrodynamic traffic flow model

The hydrodynamic model can be used to describe traffic problems in transport. When the speed of the first car is less than the speed behind it, it leads to traffic jams. When the first car's speed is faster than the cars behind it, it leads to traffic evacuation. If we consider the first car to be a piston, then the speed of the piston will cause traffic jams and traffic evacuation. In this paper, we study the piston problem for the hydrodynamic model. The formation and propagation of shock wave, rarefaction wave, delta-shock wave, and vacuum can describe the phenomena of traffic jams, traffic evacuation, severe traffic jams, and traffic evacuation with traffic volume of zero, respectively. Therefore, for different traffic phenomena, we prove the existence of shock solution, rarefaction solution, delta shock solution, and vacuum solution. In addition, we perform some representative numerical simulations.

Microfluidics-mediated Liposomal Nanoparticles for Cancer Therapy: Recent Developments on Advanced Devices and Technologies.

Liposomes, spherical particles with phospholipid double layers, have been extensively studied over the years as a means of drug administration. Conventional manufacturing techniques like thin-film hydration and extrusion have limitations in controlling liposome size and distribution. Microfluidics enables superior tuning of parameters during the self-assembly of liposomes, producing uniform populations. This review summarizes microfluidic methods for engineering liposomes, including hydrodynamic flow focusing, jetting, micro mixing, and double emulsions. The precise control over size and lamellarity afforded by microfluidics has advantages for cancer therapy. Liposomes created through microfluidics and designed to encapsulate chemotherapy drugs have exhibited several advantageous properties in cancer treatment. They showcase enhanced permeability and retention effects, allowing them to accumulate specifically in tumor tissues passively. This passive targeting of tumors results in improved drug delivery and efficacy while reducing systemic toxicity. Promising results have been observed in pancreatic, lung, breast, and ovarian cancer models, making them a potential breakthrough in cancer therapy. Surface-modified liposomes, like antibodies or carbohydrates, also achieve active targeting. Overall, microfluidic fabrication improves reproducibility and scalability compared to traditional methods while maintaining drug loading and biological efficacy. Microfluidics-engineered liposomal formulations hold significant potential to overcome challenges in nanomedicine-based cancer treatment.

Fractal structures in the chaotic advection of passive scalars in leaky planar hydrodynamical flows.

The advection of passive scalars in time-independent two-dimensional incompressible fluid flows is an integrable Hamiltonian system. It becomes non-integrable if the corresponding stream function depends explicitly on time, allowing the possibility of chaotic advection of particles. We consider for a specific model (double gyre flow), a given number of exits through which advected particles can leak, without disturbing the flow itself. We investigate fractal escape basins in this problem and characterize fractality by computing the uncertainty exponent and basin entropy. Furthermore, we observe the presence of basin boundaries with points exhibiting the Wada property, i.e., boundary points that separate three or more escape basins.

Stefan flow-inclusive mass transfer in a narrow cylindrical channel with a two-layer medium

The exploration and extraction of oil, coal, and gas reserves are closely tied to mass transfer phenomena within porous and fractured rock formations. Frequently, these processes involve the adsorption or desorption, dissolution, or evaporation of certain components on the surface of the pore channels. In these cases, Stefan hydrodynamic flows arise, and although they may be individually small, they can have a noticeable impact on mass transfer and flow structure considering particular length of the channel. The authors explore the issue of inert component diffusion from the surface of a capillary into a suspension flow. The analysis involves a two-layer flow, including a central two-phase (liquid and particles) component and a near-wall flow of the fluid carrier. A certain component from the channel’s surface permeates deep into the flow without interacting with the solid phase. In this research the authors solve a diffusion problem with boundary conditions that consider the presence of Stefan hydrodynamic flows. The calculations reveal that, depending on the magnitude of the Stefan flows and the length of the affected area, the porosity, and consequently, the viscosity of the two-phase flow zone can undergo significant variations.

SCALE FORMATION IN THE OIL AND GAS INDUSTRY AND THE TRANSITION TOWARDS «GREEN» INHIBITORS

Hydrocarbon production in oil field conditions invariably involves the joint production of significant amounts of water. Mineral salts of various compositions can precipitate from produced water under certain conditions. In the oil and gas industry, the deposition of mineral salts on the surface and underground production equipment can cause various problems, such as deterioration of reservoir properties, reduced production and premature failure of well equipment. Scale deposition can also lead to pump malfunctions, reduced efficiency of heat exchangers, reduced quality of commercial products and increased corrosion processes. Salt deposits lead to expensive restoration work, downtime in well operations and, ultimately, to an increase in the cost of produced hydrocarbons.As a result of the geochemical processes between the injected water and the formation water and the formation rock, as well as the complex composition of the formation fluids, controlling the formation of inorganic scales becomes a challenge. In the oil and gas industry, carbonate (calcium), sulfide (iron) and sulfate (calcium, barium, strontium) deposits are most often encountered. The formation of scale deposits depends on several factors, which include, but are not limited to, temperature, pressure, solution saturation and hydrodynamic flow characteristics.There are many approaches to managing scale deposits, but the most common currently is the use of chemical reagents – scale inhibitors. Traditional scale inhibitors contain phosphorus- and nitrogen-based chemicals as their active base, which can be harmful to the environment and human health. In this regard, in the world practice of oilfield chemistry, the direction of «green» chemistry is actively developing – reagents that can effectively prevent the formation of mineral salts with minimal negative impact on the environment and humans.This review discusses various scale types, methods for their removal, scale inhibitors of various natures and the mechanism of their work. Attention is also paid to «green» inhibitors and their development.

Runoff Hydrograph Analysis of HEC-RAS 2D Flow Hydrodynamics Meteorological Rain-on-Grid on Observed Watershed: A Case Study of Wiroko Sub-Watershed

In contemporary hydrological analysis, numerical models have emerged as an alternative solution for water resources planning and management, particularly in forecasting extreme events and mitigating disaster risks. HEC-RAS 2D flow hydrodynamics enables the modeling of rainfall with input from meteorological boundary condition data. Precipitation within the studied watershed can be modeled as point rainfall or area-averaged rainfall in the rain-on-grid feature of HEC-RAS 2D flow hydrodynamics. In this study, the HEC-RAS 2D flow model utilizes the diffusion wave equations (DWE) for simulating unsteady flow routing. When modeling a complex watershed, the 2D hydrodynamics model has become a viable alternative, especially concerning the watershed's physical characteristics. This study aims to assess the reliability of HEC-RAS 2D flow hydrodynamics and compare its results with the hydrograph data from the observed watershed in the Wiroko Sub-Watershed of the upper Wonogiri Dam. In this research, extreme rainfall events of 100 mm in the first hour are simulated and compared with the hydrograph data from the observed watershed. Based on the numerical model results in the Wiroko Sub-Watershed, it was determined that conforming to the land use with a Manning roughness value of 0.12 (designated as developed area-medium intensity) resulted in a peak discharge (Qp) difference of 0.8%. Meanwhile, the time to peak (Tp) value exhibited a discrepancy of 1.93 hours longer between the numerical model and the observed hydrograph.

CFD investigation of flow hydrodynamics and optimization in an industrial‐scale annular lance with swirl flow

AbstractSwirling flow has been applied in various fields due to its ability to enhance mass, heat, and momentum transfer performance. However, the generation of swirling flow occurs at the price of augmenting the pressure drop, and enhancing the friction and shear intensity of the jet with respect to the reactor wall. In the present work, the impact of geometrical configurations of the swirler on the hydrodynamics of the fluid in an industrial‐scale annular lance is investigated via the computational fluid dynamics method, with the discussion of the friction coefficient of the lance walls. It shows that the axial flow injected from the central lance is transformed into a weak swirl flow upon the introduction of swirl flow generated in the casing pipe. Within the mixing region, the interaction between axial and swirl flows results in elevated turbulent kinetic energy. Notably, under varying geometrical configuration conditions, the pressure drop between the inlet of the central pipe and the outlet is maximized. Additionally, the highest friction factor appears at a height of 1.35 m along the middle shell, with a value of 96.67.

Effect of the kinematic viscosity on liquid flow hydrodynamics in vortex mixers

The effect of the kinematic viscosity of similar fluids on liquid flow hydrodynamics and the onset of the instability were investigated to acquire information on the mixing behavior of vortex mixers. To assess the influence of the kinematic viscosity, water and two glycerin aqueous solutions with varying weight percentages (25 wt % and 50 wt %) were used. The critical Reynolds number of the flow regime transitions was found using PLIF and PIV flow-field techniques. The liquid flow hydrodynamics and gas flow dynamics in the proposed vortex mixer geometry were compared, as well. It was observed that the kinematic viscosity has a linear relation with the critical Reynolds number; however, the coefficient is different for liquids and gases. Additionally, kinematic viscosity dictates the minimum Reynolds number where the fluids have a full turn inside the chamber. It was observed that fluids having higher kinematic viscosities have a full turn at lower Reynolds numbers, and the critical Reynolds number value decreases with increasing kinematic viscosity.

The study on the multiplicity dependence of ridge behavior in pp collisions at [formula omitted] TeV at the LHC

The long-range near-side ridge phenomenon in two-particle correlation is one of the key issues in studying the strong interaction. In particular, the hydrodynamic flow effect of the quark-gluon plasma (QGP) has explained it well for heavy-ion collisions, but is limited in its ability to explain the phenomenon in small systems. The Momentum Kick Model (MKM), on the other hand, suggests a fundamental explanation of the phenomenon through the kinematic process; the high-momentum jet particles collide with medium partons, transfer their momentum to them (called the “kick” process), and induce collective motion of the kicked-partons resulting in the ridge phenomenon. This MKM has successfully described the ridge structure in heavy-ion collisions at the RHIC. Furthermore, since the ridge phenomenon in small systems is prominent in high-multiplicity events, the MKM with multiplicity dependence (MKMwM) has been studied in pp collisions at the LHC using a relationship between the number of kicked-partons and the multiplicity through the impact parameter. In this research, we extend the previous study with more recent experimental data-driven parameters and apply them to the new measurements that have a wider multiplicity range with pT and ΔΦ bins at the LHC. We also predict the ridge structure at the energies scheduled by the LHC in the upcoming Run 3 experiments.

Two-dimensional hydrodynamic electron flow through periodic and random potentials

Two-dimensional hydrodynamic electron flow through periodic and random potentials

Influence of Permeability and Shear-Thinning Behavior on the Hydrodynamics Flow Features Around Porous Square Cylinders

Abstract This article investigates the laminar flow of power-law fluids through two porous square cylinders in a side-by-side configuration. The effects of power-law index (n), Darcy number (Da), and gap ratio (g/W) are examined within ranges of g/W = 0.5–5, n = 0.4–0.8, and Da = 10−6–10−2, respectively. Two flow conditions are considered: first, for a creeping flow (unseparated flow) at Re = 1 where Darcy's law is applicable; second, for a viscous dominant flow at Re = 100, where Darcy–Forchheimer-extended model is exercised. Flow patterns behind the porous cylinders are analyzed using streamlines, velocity profiles, pressure distribution curves, and vorticity structural parameters (Г). In low permeability levels, the flow exhibits an irregular nonperiodic vortex shedding characterized by a single large vortex street far off the downstream for g/W = 0.5. However, synchronized wake patterns were observed in either antiphase or in-phase modes for higher gap ratios. Leading-edge separation with two-side recirculation induces quasi-periodicity in the flow for all g/W. It was found that increasing the permeability can prevent the leading edge separation. Additionally, a transition from antiphase to in-phase mode occurs when the permeability is altered while maintaining constant flow-time. The presence of a jet-like flow between cylinders significantly impacts unsteady wake patterns. The impact of g/W, power-law index, and permeability on drag is also examined. A jump in some flow parameters was observed at higher Re for the midrange Darcy number, but no such increase was noted for the high shear-thinning behavior. These findings provide a potential approach for improving the design of fluidic systems involving porous cylinders.

A Computational Investigation of the Influence of Seafloor Conditions on the Turbulent Flow Characteristics of an Autonomous Underwater Vehicle

The effect of the seabed on the hydrodynamics of three-dimensional autonomous underwater vehicles (AUVs) varies according to the physical conditions of the place where AUVs interact with the environmental conditions. This study examines the hydrodynamics of an AUV resembling a torpedo model while taking the influence of the seabed surface as a function of the dimensionless distances (G/D) between the torpedo and the seabed. Reynolds numbers, varying from 1 × 104 to 8 × 104, were considered. These Reynolds numbers were associated with various seabed distances falling within 0.25 ≤ G/D ≤ 1.5. To perform the simulations, governing equations were utilized and incorporated with the k–ω SST turbulence model. It has been observed that when AUVs or torpedo models operate in close proximity to the seabed surface, several key hydrodynamic parameters and flow characteristics are affected. These include the pressure coefficient (Cp), drag coefficient (CD), overall flow structures, maneuverability, and performance of the torpedo model. As the AUV or torpedo model approaches the seabed surface, the symmetrical flow pattern deteriorates. This deterioration is associated with changes in vortical flow structures under the influence of seabed surfaces. Additionally, the intensity of the shear stress (τ) near the seabed surface gradually increases as the AUV or torpedo model gets closer to it. In summary, the proximity of AUVs or torpedo models to the seabed surface causes disruptions in the flow patterns, increased shear stress, and alterations in key hydrodynamic parameters, ultimately affecting the system's performance and behavior.

Applying hydrodynamic principles and flow theory to optimize the reservoir pressure survey program without shut-in the well - Case study: Biba reservoir, Algeria

The article focuses on the importance of gathering and analyzing information related to oil and gas reservoirs, particularly parameters such as permeability (k), skin factor (S), pressure (p), and temperature (T). This data is crucial for making significant decisions in adjusting production technologies, intervening in wells, and near-well bore treatment. To obtain this information, analyzing data from tests is essential. Pressure, flow rate, and time data are collected using pressure buildup testing, where wells are produced at a constant rate and then shut-in to observe pressure increase over time. Analyzing this data allows evaluation of permeability, pressure in the drainage region, skin factor, and other parameters like static pressure. The article also discusses applying principles of hydrodynamics and flow theory to optimize well pressure survey programs without disrupting production operations. This method enables the collection of necessary information while maintaining continuous field operations and providing comprehensive technological data. The results were applied on Bali reservoir in Algeria. Information gathered from pressure survey programs not only helps fine-tune and optimize daily production procedures but also significantly contributes to updating reservoir models. This serves as a basis for future development decisions within the reservoir. The method has been successfully applied at Biba field, Algeria.