Natural Flow Research Articles

Numerical Study on the In-Service Welding Stress of X80 Steel Natural Gas Pipeline

In this study, the welding stress of in-service welding on the X80 steel pipeline was investigated using the 3D finite element method. The parameters of heat source and axial and hoop welding stress were verified in the experiment. As shown in the results, in the heat-affected-zone (HAZ) location of the pipeline and sleeve, the outer wall was predominantly under compressive stress, while the inner wall was mainly subjected to tensile stress. The hoop stress (σh) is greater than the axial stress (σa). The maximum hoop stress is primarily concentrated at the connection point between the fillet weld and the sleeve, and its value exceeds the yield strength of X80 steel. Excluding the start–end region, the axial stress distributed in the circumferential direction remains at an almost constant value. The hoop stress values exhibit an approximately symmetric distribution, with relatively higher values at 0° and 180° and relatively lower values at 90° and 270°. Compared with axial stress, the influence of natural gas pressure and flow rate on the hoop stress of the pipeline is more pronounced. When the natural gas pressure increases from 0.5 MPa to 2.5 MPa and the flow rate increases from 1 m/s to 20 m/s, the hoop stress of the pipeline increases by 3.18% and 15.42%, respectively. Moreover, the influence of the preheating temperature on the axial stress of the sleeve is highly prominent. When the preheating temperature is elevated from 20 °C to 300 °C, the axial welding stress of the sleeve increases by 115.3%. These results indicate that maintaining the natural gas pressure at 1 MPa, keeping the flow rate below 12 m/s, and controlling the preheating temperature at approximately 50 °C can enhance the performance of the fillet weld during the in-service welding of X80 steel pipelines.

Socio-Economic Impact Assessment of Hydrogen Injection in the Natural Gas Network

This study explores the feasibility parameters of a potential investment plan for injecting “green” hydrogen into the existing natural gas supply network in Greece. To this end, a preliminary profitability optimization analysis was conducted through key performance indicators such as the cost of hydrogen and the socio-environmental benefit of carbon savings, followed by break-even and sensitivity analyses. The identification of the major impact drivers of the assessment was based on the examination of a set of operational scenarios of varying hydrogen and natural gas flow rates. The results show that high natural gas capacities with a 5% hydrogen content by volume are the optimal case in terms of socio-economic viability, but the overall profitability is too sensitive to hydrogen pricing, rendering it unfeasible without additional motives, measures and pricing strategies. The results feed into the main challenge of implementing commercial “green” hydrogen infrastructures in the market in a sustainable and feasible manner.

Flow Matters: Unravelling the Interactive Influences of Flow Variation and Non‐Native Trout on Vulnerable Galaxiids

ABSTRACTUnderstanding the interactive effects of non‐native species and alterations to flow regimes is important to combat threats to freshwater communities. Low‐flow conditions may either exacerbate or offset influences of non‐natives but the mechanisms determining the direction are poorly understood. We evaluated how stream drying affected interactions between vulnerable native stream‐resident galaxiids and non‐native trout in Aotearoa, New Zealand. We electrofished (December–March) paired perennial and drying reaches containing galaxiids (Galaxias vulgaris and G. paucispondylus) to compare abundance and growth rates in streams with high abundance (n = 2), low abundance (n = 2) or no brown trout (n = 3; Salmo trutta). Low flows greatly reduced trout abundance and size, likely reducing predatory threats to galaxiids since risk is size‐related. Galaxiid densities were consistently lower in drying compared to perennial reaches of troutless streams. However, galaxiids were less affected by low flows than trout, setting the scene for an interaction between trout and low flow. In streams with high numbers of trout, galaxiid numbers were very low in perennial reaches, whereas they were moderate in drying reaches. That meant galaxiid numbers increased with a decreasing flow in streams with many trout, an indirect positive effect, although their abundance never reached the high levels of trout‐free perennial reaches. In low‐density trout streams, there were no clear differences in galaxiid abundance between reaches of different flow types. Thus, the effects of trout on galaxiids depended on the flow regime, likely driven by harsh low‐flow conditions suppressing large trout, which were more sensitive to low flow than galaxiids. Galaxiid growth rates actually increased with conspecific densities in trout streams, whereas growth rates decreased with increasing galaxiid densities in troutless streams. Thus, growth advantages for galaxiids in the presence of trout possibly helped drive these low‐flow effects on their populations in trout streams, potentially via an attractive sink‐type mechanism. Overall, although low‐flow conditions likely reduced predatory effects of non‐natives and may have indirectly bolstered growth rates of natives, populations of natives were also suppressed by low flow. Such interactive effects of flow reduction are likely common and appear controlled by relative vulnerability and size‐structured interactions and will be key to balancing the maintenance of natural flows with minimising effects of non‐native sports fish. Flow depletion might create some refuge for native fishes in the presence of a non‐native, but net effects could still be worse than no flow depletion as we observed. Thus, it will be important to ascertain how flow‐depleted reaches affect the long‐term persistence of native fish populations before relaying on flow reduction to suppress non‐natives.

Enhancing Long-Term Viability of Energy Pile with Heat Sink Systems in Tropical Monsoon Climates: Implementation Strategies and Performance Analysis

Energy piles, a form of ground-source heat pump system integrated into building foundations, show great potential for reducing building energy consumption associated with fossil fuels. While it excels in climates where cooling demand matches heating, its effectiveness faces challenges in tropical monsoon regions characterized by hot summers and cool winters. In such climates, cooling demand dominates, leading to significant thermal accumulation over time, which diminishes the long-term viability of energy pile systems. This study focuses on the long-term thermal behavior analysis of an energy pile system installed in a representative office building. Our approach begins with an examination of short-term behavior, followed by the creation of a simplified model. Using this model, we analyze the long-term behavior of different systems, including the standard energy pile and combinations with various solutions: natural groundwater flow and synthetic heat sink systems. Key outcomes are evaluated based on entering water temperature (EWT), soil temperature, and energy efficiency ratio (EER), while also comparing energy savings with conventional air conditioning systems. Major findings include: (1) Standard energy pile systems without any mitigation measures achieve only a 15.3% energy savings initially and may cease functioning after approximately 10 years, (2) Energy pile systems using specific solutions can achieve a maximum saving ratio of 50%, typically ranging from 30% to 45%, while maintaining stability over the designated lifespan, (3) Higher EER and saving ratios correlate with increased groundwater flow and larger heat sink systems, however, the relationship is nonlinear, emphasizing the need for tailored design under varying geology and climate conditions. This study provides essential insights into energy pile systems design and practical guidance, along with expected energy savings in tropical monsoon climates for future application.

Opening the black box: Think Aloud as a method to study the spontaneous stream of consciousness.

Asking participants to Think Aloud is a common method for studying conscious experience, but it remains unclear whether this approach alters thought qualities-such as meta-awareness, rate of topic shifts, or the content of thoughts in task-absent conditions. To investigate this, we conducted two studies comparing thinking aloud to thinking silently. In Study 1, 111 participants alternated between 15-minute intervals of verbalizing and silently reflecting on their stream of consciousness in a counterbalanced design. A subset also reported topic shifts intermittently via self- and probe-catching methods. Results showed that the stream of consciousness was minimally reactive to the Think Aloud protocol, with no significant differences in meta-awareness and topic shifting rates. Moreover, among 21 thought qualities and 18 content topics analyzed, only three qualities (private thoughts, mind blanking, and session difficulty) and one topic (partner, intimacy, love, and sexual matters) differed between Think Aloud and Silent Think. In Study 2, 102 participants either did Think Aloud or Silent Think while responding to thought probes. Findings replicated the lack of differences in the frequency and meta-awareness of topic shifts between Think Aloud and Silent Think. Furthermore, no differences in reported cognitive load were observed between the two conditions. These results emphasize the value of the Think Aloud procedure for examining the stream of consciousness, demonstrating its reliability and minimal impact on the natural flow of thoughts. Thus, Think Aloud offers a robust model system for examining the otherwise unverbalized stream of consciousness in task-absent contexts.

Investigating suspended sediment dynamics in the Spöl and Inn rivers during experimental floods using high-resolution monitoring.

Experimental floods serving environmental or ecological purposes (e-floods) represent a strategic approach to managing sediment within river systems altered by hydropower operations and other regulation. The absence of natural sediment transport due to minimum flows below dams and intakes leads to various ecological challenges, including river incision and habitat degradation. By releasing water stored behind dams, e-floods aim to mimic natural flow regimes, facilitating the redistribution of fine sediments that have clogged the riverbed and rebuilding aquatic habitats. Our research examines the effects of e-floods on the Spöl River, which flows into the Inn River in southern Switzerland. Through the deployment of a suspended sediment concentration (SSC) sensor network, 4 sensors in 2021 and 7 sensors in 2023, we monitored the release of previously stored sediment and the propagation of suspended sediment waves triggered by these e-floods at a high temporal resolution (1-2.5 mins). Our findings reveal SSC pulsations above 5 gL-1 (lasting 3 h) and above 8 gL-1 for at least 30 min, in both 2021 and 2023, respectively, which were larger in amplitude and lasting longer than previously measured, surpassing established thresholds. The peaks reached were 12.0 gL-1 (2021) and 10.8 gL-1 (2023). Moreover, the sediment wave was observed to extend into the Inn river, leading to potential siltation and ecological impacts downstream. We found a total fine sediment load of 1,297 ± 75 t and 1,936 ± 133 t (in 2021 and 2023, respectively) delivered by the Spöl e-floods to the Inn, which is 0.8-1.1% of the total annual fine sediment load in the Inn. A simple steady-state solution to the advection equation suggests that for suspended sediments to settle before reaching the Austrian border, the discharge and SSC of the Spöl and the discharge of the Inn must all be taken into consideration. We provide a proof-of-concept that high-resolution fine sediment sensing should accompany e-flood planning in order to capture the fluctuations in SSC during the release, to identify possible fine sediment inputs either from the dam or instream sources, such as river bed, banks and floodplain, and to provide first-order estimates of the fine sediment loads and their propagation downstream. Future work can use data from such a network to develop predictive models and adaptive management strategies to mitigate adverse ecological effects while optimizing sediment redistribution efforts.

Estimation of the Water Footprint of Wood Construction in Chile Using a Streamlined Input–Output-Based Model

Wood construction is often proposed to reduce the construction sector’s greenhouse gas emissions due to its carbon sequestration potential. However, forestry significantly impacts natural water flows and increases water use—a critical concern in Chile. This study evaluates the water footprint of wood construction in Chile, considering direct and indirect water consumption under various scenarios. An input–output model was developed to quantify economic interactions, incorporating a new wood-construction sector based on data from a model house. An environmental extension matrix was also created to account for blue water (groundwater and surface water extraction) and green water (rainwater absorbed from soil) consumption. Future scenarios for the residential building sector were defined based on different growth rates for wood-based construction and current construction methods, and the model was resolved using the scenarios as demand vectors. The results indicate that wood construction’s water footprint is 2.38–2.47 times higher than conventional construction methods, with over 64% linked to forestry’s green water demand. By 2050, increased wood construction could raise the sector’s total water footprint by 30.0–31.8%. These findings underscore the need to assess water consumption as a critical sustainability parameter for wood construction and highlight the value of tools like the water footprint to guide decision-making.

Flowing With the Syntax: The Influence of Taoism on Syntactic Priming Effects

Syntactic priming is a linguistic phenomenon where the exposure to a specific grammatical structure increases the likelihood that the same structure will be used in subsequent language production. Previous research has shown that these syntactic processes are influenced by a broad range of linguistic, cognitive, and social factors. In the present research, we focused on the role of religious systems in shaping syntactic priming in dialog. Based on the observation that the Taoist concept of “moving with flow” encourages individuals to adapt to the natural flow of life and circumstances, we hypothesized that Taoists might modify their syntactic choices to foster better connections with their interlocutors. We conducted two studies to test our theoretical perspective. As predicted, Study 1 found that Taoists were more likely to mirror the syntax used by their interlocutors in dialog than their atheist counterparts. In Study 2, we compared the magnitude of syntactic priming effects between Taoists and Buddhists. The results showed that Taoists demonstrated a stronger preference for using the same syntactic structure as their conversational partners than Buddhists. In sum, our findings provide the first empirical evidence that beliefs and values associated with religious systems exert a significant influence on syntactic priming effects.

Identification of Oligosaccharide Isomers Using Electrostatically Asymmetric OmpF Nanopore.

Glycans, unlike uniformly charged DNA and compositionally diverse peptides, are typically uncharged and exhibit rich stereoisomeric diversity in the glycosidic bonds between two monosaccharide units. This heterogeneity of charge and the structural complexity present significant challenges for accurate analysis. Herein, we developed a novel single-molecule oligosaccharide sensor, OmpF nanopore. The natural electroosmotic flow within OmpF provides robust driving force for unlabeled neutral oligosaccharides, accomplishing a detection concentration as low as 6.4 μM. Furthermore, the asymmetric constriction zone of OmpF was employed to construct a stereoselective recognition site, enabling sensitive identification of glycosidic bond differences in cell lysate samples. Assisted by machine learning algorithms, a recognition accuracy of 99.9% for tetrasaccharides differing in only one glycosidic bond was achieved. This nanopore sensor offers a highly sensitive analytical tool with a broad dynamic range for the chiral recognition of oligosaccharides at low concentrations, applicable to both low-abundance and practical samples.

Identification of Oligosaccharide Isomers Using Electrostatically Asymmetric OmpF Nanopore

Glycans, unlike uniformly charged DNA and compositionally diverse peptides, are typically uncharged and exhibit rich stereoisomeric diversity in the glycosidic bonds between two monosaccharide units. This heterogeneity of charge and the structural complexity present significant challenges for accurate analysis. Herein, we developed a novel single‐molecule oligosaccharide sensor, OmpF nanopore. The natural electroosmotic flow within OmpF provides robust driving force for unlabeled neutral oligosaccharides, accomplishing a detection concentration as low as 6.4 μM. Furthermore, the asymmetric constriction zone of OmpF was employed to construct a stereoselective recognition site, enabling sensitive identification of glycosidic bond differences in cell lysate samples. Assisted by machine learning algorithms, a recognition accuracy of 99.9% for tetrasaccharides differing in only one glycosidic bond was achieved. This nanopore sensor offers a highly sensitive analytical tool with a broad dynamic range for the chiral recognition of oligosaccharides at low concentrations, applicable to both low‐abundance and practical samples.

Impact of Long Well Screens on Monitoring of the Freshwater-Saltwater Transition Zone.

Deep monitoring wells with long screens crossing the transition zone between freshwater and saltwater are often used in coastal areas to characterize fresh groundwater resources and the depth of saline groundwater. However, past studies have demonstrated that long-screen wells can lead to biased observations of the transition zone, since vertical flow within the borehole can modify the shape and elevation of the transition zone in and around the borehole compared to undisturbed conditions without a well. Here, field observations and variable-density numerical flow simulations are used to evaluate, under natural flow conditions, how the installation of long-screen wells can provide time-varying biased observations of the freshwater-saltwater transition zone, and how various aquifer and well parameters affect the magnitude of these biases. Results show that long-screen wells can lead to a more dispersed interface, an upward displacement of the transition zone of between 5 and 10 m, and a salinity decrease in the saltwater portion of the well on the order of 10 to 15 g/L. The perturbations take up to 5 years to fully develop and stabilize. The degree of displacement depends on the screen diameter, screen length, aquifer anisotropy, and hydraulic conductivity, whereas the displacement is independent of the distance of the well from the coast. This analysis provides insight into which well and aquifer characteristics increase the risk of obtaining biased observations in long-screen wells, and provides orders of magnitude for these biases.

Study on fluid flow as well as heat transfer characteristics of high-speed solid-rotor motor cooled by natural gas based on turbulent Taylor-Couette vortex

The High-speed Solid-rotor Induction Motor Cooled by Natural Gas (HSIMCNG), is suitable for integrated compressors in natural gas pipeline transportation due to its high mechanical strength. In order to further improve the cooling effect of the motor and lighten the motor weight, it is of great significance to research on the natural gas flow, heat transfer characteristics and motor structure optimization. Firstly, the natural gas flow state characteristics in the 160 kW HSIMCNG are investigated in this article. The natural gas Taylor vortex distribution in the air gap is analyzed, and the natural gas flow as well as heat transfer characteristics are obtained. Secondly, in the cooling structure of the motor with slotted rotor, the impact of the slot on the natural gas flow state is further explored in detail by combining the mechanism of the Taylor vortex on the natural gas turbulent kinetic energy, and the natural gas heat transfer effect is clarified. Finally, the variation characteristics of the natural gas radial and tangential velocities with the spatial position in the motor with different ventilation cooling structures are compared and analyzed in depth, and the key factors affecting the natural gas Taylor vortex flow and heat transfer effect are determined.

COSST: A tool to facilitate seed provenancing for climate‐smart ecosystem restoration

Abstract Selecting the best seed sources is a key step in ecological restoration planning especially under climate change. Seed‐provenancing strategies include composite, aiming to reproduce natural gene flow; predictive, focusing on future climate adaptation; and climate‐adjusted, a combination of composite and predictive. Yet, implementing different seed‐provenancing principles remains a challenge. To fill this methodological gap, we developed the Climate‐Oriented Seed‐Sourcing Tool (COSST), a tool built in R capable of suggesting priority areas for seed sourcing according to composite, predictive, or climate‐adjusted strategies, as well as the restoration site and focal species. The tool derives its inputs from species distribution models, which require occurrence and climate data only. COSST accommodates multiple climatic variables, weights the variables according to species‐specific sensitivities, and accounts for uncertainties between climate forecasts. We demonstrated the flexibility of COSST using Caryocar brasiliense (pequi), a tree native to the Brazilian Cerrado, as a case study. The tool identified optimal areas for collecting C. brasiliense seeds and estimated the proportion of seeds to be sourced from various suppliers. We made available an R code for running COSST along with a Shiny application for data visualization. Synthesis and applications. Our tool can guide where to source seeds for species lacking range‐wide information on genetic structure, which is the case for a substantial proportion of the tropical flora, where ecosystem restoration is of paramount importance.

Precision of in vivo pressure gradient estimations using synthetic aperture ultrasound.

Non-invasive estimation of pressure differences using 2D synthetic aperture ultrasound imaging offers a precise, low-cost, and risk-free diagnostic tool. Unlike invasive techniques, this preserves natural blood flow and avoids the limitations of devices that occupy lumen space. This paper evaluates a previously published estimator, modified to incorporate Singular Value Decomposition (SVD) echo-cancellation, using data from ten healthy volunteers and one patient. It is hypothesized that the estimator will enable precise pressure differences from the common carotid artery with a coefficient of variation of approximately 10% over a 10-second data acquisition period. Here, precision is essential to demonstrate the method's consistency and its ability to differentiate between healthy and diseased arteries at the earliest possible stage. Data are acquired using a GE-9L-D, 5.2 MHz linear transducer connected to a Vantage 256 research scanner. The estimator was applied to the left common carotid artery of ten healthy volunteers, with precision being evaluated over the recorded heart cycles by using the coefficient of variation. Eight out of ten individuals showed precision below 10%, whereas two individuals showed precision above 20%. The best precision was attained by subject_03 with a coefficient of variation of 4.64% (16.1 Pa) and the worst precision was attained by subject 09 with a coefficient of variation of 23.3% (30.2 Pa). The average range of pressure differences across volunteers (from maximum positive to maximum negative pressure difference) was 297 Pa when measured across a 14 mm streamline. The corresponding average coefficient of variation was found to be 9.95% (24.6 Pa). A comparison of peak systolic velocities between the experimental scanner and the reference scanner demonstrates a strong positive linear correlation (R2 = 0.76). The corresponding slope of the linear best fit is 0.95, indicating that the relationship between the two scanners is close to a one-to-one match, with the experimental scanner's measurements being slightly less than those of the reference scanner. Finally, data attained from a single patient example shows pressure differences ranging from -61.81 Pa to 1240.82 Pa with blood velocities as high as 1.73 m/s, which is significantly higher than seen in any of the healthy volunteers, supporting the likelihood of differentiating between stenosis grades in future studies. While this study is limited to 10 healthy volunteers and one patient, a different study design is needed to quantify the severity of stenosis and correlate it with pressure differences.

Increasing the efficiency of bioreactor operation for cultivation of methane-oxidizing bacteria under conditions of decreasing carbon dioxide concentration in the cultural liquid

Objectives. The work set out to develop a bioreactor that incorporates a carbon dioxide removal unit within the apparatus gas phase, which is capable of operating without the need for supplementary compression apparatus. As part of testing the developed equipment in order to ascertain its capacity for enhanced biomass production, the principal fermentation system parameters that facilitate the optimal bioreactor productivity in conditions of carbon dioxide removal from the apparatus gas phase were identified.Methods. A series of tests were conducted on the fermentation unit with the objective of controlling the oxygen and carbon dioxide content in the gas phase of the bioreactor. This was achieved using an in-line gas analyzer fitted with electrochemical sensors. The oxygen and carbon dioxide content in the gas phase was determined by means of gas chromatography. The oxygen and natural gas flow rates were determined using a thermal electronic flow controller equipped with thermoresistive elements. The oxygen content of the cultural liquid was determined by means of an optical oxygen sensor with integrated transducer. The pH level in the bioreactor was monitored and maintained using an electrochemical pH sensor.Results. The efficacy of the newly devised jet-type bioreactor design, which permits the incorporation of a carbon dioxide removal unit into the fermentation system without requiring supplementary compression apparatus, was evaluated through experimentation. The system was tested with the carbon dioxide removal unit included in the design, resulting in a 64% increase in bioreactor productivity and a 18% reduction in oxygen consumption as a component of the gas supply.Conclusions. The operational parameters of a technological bioreactor that facilitate a stable continuous process of bacterial cultivation were identified.

Hybridizing evolutionary algorithms and multiple non-linear regression technique for stream temperature modeling

Abstract The present study hybridizes the new-generation evolutionary algorithms and the nonlinear regression technique for stream temperature modeling and compares this approach with conventional gray and black box approaches under natural flow conditions, providing a comprehensive assessment. The nonlinear equation for water temperature modeling was optimized using biogeography-based optimization (BBO) and invasive weed optimization (IWO), simulated annealing algorithm (SA) and particle swarm optimization (PSO). Two black box approaches, a feedforward neural network (FNN) and a long short-term memory (LSTM) network, were also employed for comparison. Additionally, an adaptive neuro-fuzzy inference system (ANFIS) served as a gray box model for river thermal regimes. The models were evaluated based on accuracy, complexity, generality and interpretability. Performance metrics, such as the Nash–Sutcliffe efficiency (NSE), showed that the LSTM model achieved the highest accuracy (NSE = 0.96) but required significant computational resources. In contrast, evolutionary algorithm-based models offered acceptable performance while reducing the computational complexities of LSTM, with all models achieving NSE values above 0.5. Considering interpretability, accuracy and complexity, evolutionary-based nonlinear models are recommended for general applications, such as assessing thermal river habitats. For tasks requiring very high accuracy, the LSTM model is preferred, while ANFIS provides a balanced trade-off between accuracy and interpretability, making it suitable for engineers and ecologists. While all models demonstrate similar generality, this model is developed for a specific location. For other locations, independent models with a similar architecture would need to be developed. Ultimately, the choice of model depends on specific objectives and available resources.

Spontaneous net flow generation using passive artificial cilia in the nucleate boiling region

The occurrence of spontaneous net flows in nature is fascinating. Here, we report spontaneous net flow generation using passive artificial cilia consisting of directional fabric in the nucleate boiling regime. Surprisingly, by placing simple ordinary flocking rayon fibers at an angle of approximately 18 degrees on a base cloth on the circular wall in a container as the artificial cilia, we observed the circular flow of the angular velocity of up to ∼2 rad/s (the average velocity of up to ∼34 mm/s) in the nucleate boiling regime. Moreover, by the observation of a high-speed camera (960 fps), we found that the bubbles rise obliquely at a high velocity of about 80–180 mm/s, which drives the net flow. Our findings should contribute to a better understanding of spontaneous flows in nature and should be applied to utilize unused heat, such as factory waste heat effectively.

Non-hydrostatic depth-integrated models for dam break flows through rigid-emergent vegetation

Dam failures can trigger catastrophic downstream flooding, threatening lives, and infrastructure. Vegetation acts like a natural dam break flow buffer, dissipating energy, reducing wave height and celerity. This highlights importance of vegetation in flood mitigation strategies. Few existing numerical models consider how vegetation affects dam breaks. This is because it is difficult to calculate vegetation drag force in unsteady rapidly varied flows. This study addresses this gap by developing a non-hydrostatic depth-integrated model to simulate the effect of rigid emergent vegetation on dam break flows under various flow conditions. The model was validated with experimental data. Vegetation was simulated with wooden cylinders with different coverage areas and densities within a straight channel. Three dam break scenarios were investigated in the experiment using different Froude numbers to represent diverse flow regimes. The non-hydrostatic depth-integrated model of the General Bottom Velocity method (GBVC4- DWL) was developed to incorporate the vegetation effect through the drag force equation for non-uniform open channel flows. The results show that rigid emergent vegetation significantly reduces wave celerity and height, particularly downstream, demonstrating its importance in flood mitigation. The numerical model accurately predicted wave behaviour outside the vegetation zone but have difficulties within it, highlighting the need for the model to be improved to capture complex vegetation-flow interactions.

Magnetohydrodynamic unsteady natural convection slip flow in a vertical parallel plate microchannel heated with constant heat flux.

This research presents a numerical study over the unsteady natural convection of an electrically conducting fluid in an open-ended vertical parallel plate microchannel under uniform and asymmetric heat flux subjected to a uniform lateral magnetic field. Slip velocity, as well as temperature jump at channel walls, are modeled using a first-order model. The effects of Knudsen number)Kn(, heat flux ratio)rq(, Grashof number)Gr(, and Hartmann number)M(on mass flow rate, the maximum temperature of the wall, and average Nusselt (Nu) as a function of time are discussed. In this research, the flow in the limit of 0≥ M≥2; 0≥Kn≥0.1; 0.1≥ rq≥1, and 0.0001≥ L≥0.01 were simulated numerically. Furthermore, and study is conducted on steady-state velocity and temperature profiles. The research showed that increasing the Ha value, causes a reduction in the mass flow and an increase in the maximum temperature of the wall with respect to time. As M increases, the average Nusselt number as a function of time diminishes. Also, these variables present at least one overshoot or undershoot in time. The overshoot and undershoot decrease with increasing Ha. It is also revealed that the magnetic force effect decreases the fluid flow and thermal behavior with an increase in Kn. In addition, in higher Gr, magnetic force influence on profiles of velocity and temperature decreases for all rq and Kn values. Moreover, the magnetic field has no significant effect on the time at which steady state condition is attained for all rq and Gr number values.

Genetic Rescue of the Dinaric Lynx Population: Insights for Conservation From Genetic Monitoring and Individual-Based Modelling.

Inbreeding depression poses a severe threat to small populations, leading to the fixation of deleterious mutations and decreased survival probability. While the establishment of natural gene flow between populations is an ideal long-term solution, its practical implementation is often challenging. Reinforcement of populations by translocating individuals from larger populations is a viable strategy for reducing inbreeding, increasing genetic diversity and potentially saving populations from extinction. The Dinaric population of Eurasian lynx (Lynx lynx) has faced high inbreeding levels, with effective inbreeding reaching 0.316 in 2019, endangering the population's survival. To counteract this, population reinforcement was implemented between 2019 and 2023, involving the translocation of 12 individuals from the Carpathian Mountains to the Dinaric Mountains of Slovenia and Croatia. We conducted comprehensive genetic monitoring in this area, gathering 588 non-invasive and tissue samples, which were used for individual identification and estimation of population genetic parameters. We used stochastic modelling to assess the long-term viability of the Dinaric lynx population post-translocation and formulate effective conservation strategies. The model predicts that, despite significant improvement of genetic diversity after translocations, inbreeding will return to critical levels within 45 years. Our results highlight the fact that reinforcement is just the first step and that long-term genetic management is needed to keep the population from sliding back towards extinction. The Dinaric lynx population serves as a compelling example of genetic rescue. The lessons learnt here will be essential for ensuring the viability of the Dinaric lynx in the future and also provide a useful template for conservation of other populations and species facing similar threats.