Regional Flow Research Articles

Geothermal parameter assessment in the Southwestern Sokoto Basin, Nigeria, using spectral analysis (centroid method)

This study utilized spectral analysis (centroid method) to assess geothermal parameters in the southwestern part of the Sokoto Basin, Nigeria. The high-resolution airborne data comprised forty-nine (49) overlapping blocks, and each block was divided into 55x55 km to evaluate essential parameters such as depth to the top boundary (Zt ), centroiddepth (Zo), and magnetic source bottom (Zb = 2Zo-Zt ). The analysis revealed variable Curie points depths (CPD), ranging from 3.89 km to 26.56 km. The lowest CPD is primarily associated with basement rocks within anomalies A, B, C, D, E, F, G, H, and I, with an average CPD of 9.16 km. Furthermore, the thermal gradients ranged from 21.84 ◦C/km to 149.10 ◦C/km, with an average thermal gradient of 73.30 ◦C/km. The heat flow exhibited variations between 54.81 mW/m² and 374.24 mW/m², with average heat flow of 180.4 mW/m², indicating significant geothermal potential zones. The high thermal gradients and heat flow regions were identified, around anomalies A, B, and C. Additionally, temperature gradients identified at shallow depths ranged from 110 ◦C/km to 150 ◦C/km. The results reveal the presence of high-temperature points and anomalous geothermal potentials, particularly within anomalies A, B, and C, thus requiring further for sustainable geothermal energy generation in the study area.

Machine learning approach to predict flow fields induced by internal solitary waves acting on mid-water structures based on particle image velocimetry experiments

Mid-water structures (MWSs) have important applications in the ocean to minimize the effects of environmental factors in the surface ocean and to avoid the effects of high pressure on the seabed. However, their operational positions are vulnerable to internal solitary waves (ISWs), which poses a significant challenge to the safe functioning of MWSs. Consequently, there is a pressing need to explore the flow field characteristics surrounding MWSs under the action of ISWs to establish a reliable foundation for structural design. In this study, experimental investigations were conducted to analyze the flow fields induced by ISWs acting on MWSs, employing the particle image velocimetry (PIV) method. The intricate details of the flow fields around the structure were thoroughly analyzed, and the impact of the structure's submerged depth on the ISW-induced flow fields was discussed. A machine learning approach is utilized to develop an Artificial Neural Network (ANN) model aimed at predicting the flow fields of ISWs. The experimental results are compared and analyzed alongside the predicted outcomes, focusing on the anomaly region, the tail field region, and the occluded region. The results show that the presence of the structure complicates the flow characteristics in the tail flow regions, and the flow patterns are constantly changing. The characteristics of the ISW flow fields around the structure vary with the different submerged depths of the MWS. Positioning the MWS above the wave trough results in an ascending trend followed by a descending trend in the strength of the surrounding flow field with increasing submerged depth. The ANN predictions for different types of regions of the flow fields show satisfactory accuracy. The model closely matches the PIV results in predicting the extremes and positions of horizontal velocities in the tail flow fields at different stages of ISW trough propagation. The ANN model can be recommended for predicting the flow fields of ISWs acting on MWSs. This study offers comprehensive insights into the characteristics of the flow fields induced by ISWs acting on MWSs, emphasizing the valuable contribution of machine learning methods to the field of fluid dynamics.

PCSK9 expression in fibrous cap possesses a marker for rupture in advanced plaque.

To date, PCSK9 inhibitors are well known for eliminating cardiac and cerebral artery ischemia events by lowering the serum lipid level. However, the pathophysiological value of in-plaque PCSK9 expression is still unclear. Advanced plaques removed by carotid endarterectomy were sectioned and stained to identify the PCSK9 expression pattern and its co-expression with rupture-relevant markers. To investigate the correlation of PCSK9 expression with regional blood shear flow, hemodynamic characteristics were analyzed using computational fluid dynamics, and representative parameters were compared between PCSK9 positive and negative staining plaques. To explore this phenomenon in vitro, human aortic vascular smooth muscle cells were used to overexpress and knock down PCSK9. The impacts of PCSK9 modulations on mechanical sensor activity were testified by western blot and immunofluorescence. Real-time polymerase chain reaction was used to evaluate the transcription levels of downstream rupture-prone effectors. PCSK9 distribution in plaque preferred cap and shoulder regions, residing predominantly in smooth muscle actin-positive cells. Cap PCSK9 expression correlated with fibrous cap thickness negatively and co-expressed with MMP-9, both pointing to the direction of plaque rupture. A hemodynamic profile indicated a rupture-prone feature of cap PCSK9 expression. In vitro, overexpression and knockdown of PCSK9 in human aortic vascular smooth muscle cells has positive modulation on mechanical sensor Yes-associated protein 1 (YAP) activity and transcription levels of its downstream rupture-prone effectors. Serial section staining verified in situ colocalization among PCSK9, YAP, and downstream effectors. Cap PCSK9 possesses a biomarker for rupture risk, and its modulation may lead to a novel biomechanical angle for plaque interventions.

Experimental investigation of the structure of plane turbulent wall jets. Part 1. Spectral analysis

Plane turbulent wall jets are traditionally considered to be composed of a turbulent boundary layer (TBL) topped by a half-free jet. However, certain peculiar features, such as counter-gradient momentum flux occurring below velocity maximum in experiments and numerical simulations, suggest a different structure of turbulence therein. Here, we hypothesize that turbulence in wall jets has two distinct structural modes, wall mode scaling on wall variables and free-jet mode scaling on jet variables. To investigate this hypothesis, experimental data from our wall jet facility are acquired using single hot-wire anemometry and two-dimensional particle image velocimetry at three nozzle Reynolds numbers 10 244, 15 742 and 21 228. Particle image velocimetry measurements with four side-by-side cameras capture the longest field of view studied so far in wall jets. Direct spatial spectra of these fields reveal modal spectral contributions to variances of velocity fluctuations, Reynolds shear stress, shear force, turbulence production, velocity fluctuation triple products and turbulent transport. The free-jet mode has wavelengths scaling on the jet length scale ${z_{T}}$ , and contains two dominant submodes with wavelengths $5{z_{T}}$ and $2.5{z_{T}}$ . The region of flow above the velocity maximum shows the presence of the outer jet mode whereas the region below it shows robust bimodal behaviour attributed to both wall and inner jet modes. Counter-gradient momentum flux is effected by the outer jet mode intruding into the region below velocity maximum. These findings support the hypothesis of wall and free-jet structural modes, and indicate that the region below velocity maximum could be much complex than a conventional TBL.

Controlling electrothermal behavior of Metal–Carbon hybrid wire in free molecular flow region

We investigated the heat loss of the metal wire to the gases in the free molecular region, whose pressure is below 10−3 Pa. The heat transfer characteristics at the interface between the metal surface and the gases are only accessible when the conductional heat loss along the wire is comparable to or less than 100 nW/K. Unfortunately, such an infinitesimal heat flow is not controllable from typical metal wire. For this reason, we have synthesized a new material, metal-carbon hybrid wire (MCHW). In the free molecular flow region, the resistance of MCHW is inversely proportional to the pressure (P), R∼1/P, regardless of gas species, which contradicts the gas-dependent heat loss theory. At a pressure <1 × 10−4 Pa, we observe a deviation from reciprocal linearity attributed to a growing radiational heat loss. Our results realize the thermal conductive sensing of the pressure below 10−5 Pa, which has been unprecedented.

Effect of highway greenbelt constrution on groundwater flow in a semi-arid region.

The highway greenbelt, vigorously promoted in arid and semi-arid areas, has obvious impacts on beautifying the environment, absorbing dust, reducing noise, and maintaining soil and water. Moreover, it affects the characteristics of how water resources are distributed and the regional groundwater cycle. However, the impact of highway greenbelt construction on groundwater flow in semi-arid areas is unknown. The Hubao Highway greenbelt in the north part of the Tumochuan Plain was studied as an example. The paper combines field investigation, remote sensing and mathematical modeling to quantify the impact of highway green space construction on regional groundwater circulation. The results showed that: Trees, shrubs and grasses were the dominant vegetation types in the landscaped area, accounting for 42.17% of the studied area. The total evapotranspiration water consumption of the green belt during the growing season was 471.35 × 104m3. The groundwater recharge in the study area was mainly derived from the lateral recharge in front of the mountain, and the main discharge was the evapotranspiration water consumption of the green belt. This evapotranspiration accounts for 3.31% of the total groundwater recharge. Under the condition that the recharge in front of the mountain remains constant, the evapotranspiration water consumption of the green belt will still have an increasing trend in the future. Appropriate planting of poplar and other high water-consuming trees may be the best way to mitigate the adverse effects of greenbelt evapotranspiration on groundwater resources. The results of this study provide valuable insights for environmental protection and infrastructure development in similar areas.

Tracking the global anthropogenic gallium cycle during 2000–2020: A trade-linked multiregional material flow analysis

Byproduct metals are essential to global low carbon transition since they are irreplaceable in modern renewable energy technologies. Gallium (Ga) is classified as one critical byproduct metal due to its extensive use in electronic applications and low carbon technologies, as well as its limited resource endowment. It is urgent to uncover the global and regional Ga stocks and flows so that the potential supply risks can be mitigated. This study maps the global and regional Ga cycles for the period of 2000–2020 by employing a trade-linked multiregional material flow analysis (MFA) method. Our results show that 79% of the global Ga co-mined from bauxite ended up in red mud or entered the aluminum cycle as an impurity, indicating a significant recycling potential. Different involved regions have different but complementary roles in the global Ga supply chain. China dominates the global primary Ga production, accounting for 97% of the global total in 2020. Japan and the United States are key players in high-purity Ga refining and rely on Ga to support their electronic devices manufacturing. Unfortunately, Ga recycling practices are still not occurring due to the low Ga concentrations in major applications. Since the global demand for Ga will continue to grow in the near future, it is urgent to initiate collaborative efforts so that Ga recycling can be enhanced. These efforts are critical to ensure the sustainable Ga supply and facilitate the global transition toward low carbon development.

Geological modeling of a tectonically controlled hydrothermal system in the southwestern part of the Pannonian basin (Croatia)

Geothermal energy is an important resource in the green economy transition. For the preservation of a geothermal resource it is crucial to assess its renewability and the sustainability of the exploitation. These aspects are influenced by the interaction among the physical, chemical, geological, and hydrogeological processes. The reconstruction of the geological assemblage allows the detailing of the geometries of the reservoir and fracture systems that influence the fluid flow and the water/rock interaction. The control of regional/local scale fault and fold systems on the development of the Daruvar hydrothermal system (DHS), located in Croatian part of the Pannonian basin, is detailed in this work. Field investigations were conducted to collect structural data on strata orientation and fault/fracture systems. The dataset was integrated with geological and geophysical data to develop composite geological profiles and a 3D geological model. Results display a pattern of generally N-S and E-W striking folds and cogenetic fracture systems with orientations parallel to the fold axes. The geological reconstruction was integrated with geophysical, hydrogeological, and geochemical data to propose a conceptual model of the DHS. The DHS is a topographically driven system hosted in a Mesozoic carbonate reservoir where E-W striking fracture systems are regional flow paths that enable infiltration of meteoric water to 1 km depth and its reheating in its reservoir area. In Daruvar, an anticline and fault/fracture systems accommodate the uplift of reservoir to shallow depths, promoting the bedrock fracturing and increase of the permeability field. These conditions favor the localized upwelling of thermal water resulting in four thermal springs (38°C and 50°C) in Daruvar city area. This work highlights the importance of employing a multidisciplinary approach to detail the complex interaction among the processes driving the geothermal resource.

Large-Eddy Simulations of Flow over a Backward-Facing Ramp with a Wall-Mounted Cube

Passive flow control devices, such as vortex generators (VGs), can effectively modulate the turbulent boundary layer flow near regions of adverse pressure gradients, but the interactions between the salient flow structures produced by VGs and those of the separated flow are not fully understood. In this study, a spatially evolving turbulent boundary layer interacting with a wall-mounted cube ahead of a backward-facing ramp is investigated using wall-resolved large-eddy simulations for a Reynolds number of 19,600, based on the inlet boundary layer thickness and freestream velocity. Different cube configurations are examined to isolate the effects of cube height and streamwise position. The large counter-rotating flow produced by the larger cubes generated more turbulent kinetic energy, thereby resulting in smaller separated regions over the ramp. Although significantly lower levels of turbulent kinetic energy dissipation than production are observed in the outer flow regions of the horseshoe vortex and in the induced counter-rotating flow, the spatial distribution of dissipation is similar to that of the turbulent kinetic energy. When the upstream position of an isolated single cube, relative to the leading ramp edge, is more than three cube heights, the streamwise decay of the counter-rotating flow results in lower levels of turbulent kinetic energy.

Porous structures impact on particle dynamics of non-Brownian and noncolloidal suspensions

This study aims to provide valuable insights into the impact of porous structures on particle dynamics in non-Brownian, non-colloidal suspension flows at very low Reynolds numbers. Two experimental approaches, Particle Image Velocimetry (PIV) with refractive index matching and Optical Flow Tracking Velocimetry (OFTV) were employed to analyze very dilute suspensions over various porous media models. The study considered three different porous structures with permeabilities ranging from 0.7 to 0.9 and three different thicknesses ranging from 0.2 cm to 0.5 cm, while the suspension bulk volume fraction was maintained at 3 %. In the PIV analysis, we observed that decreasing the porous permeability resulted in the maximum velocity location within the free flow region moving closer towards the interface between the flow and the porous media. We further quantified the effect of the porous structure on the suspension by characterizing interface properties, such as dimensionless slip velocity, shear rate, and slip length. These interface properties were found to be influenced by both the thickness and permeability of the porous media. Next, we analyzed particle migration due to the presence of porous structures using OFTV for very dilute suspensions of 1 %, 2 %, and 3 %, considering a porous medium with known physical properties and thickness. The study revealed two local concentration maxima: one within the free flow region on top of the rod arrays used to create the porous structure and a second along the rods' centerline inside the porous media model.

Investigating three-dimensional vortex evolution in centrifugal pump under rotating stall conditions using tomographic particle image velocimetry

A rotating stall in centrifugal pumps commonly occurs under off-design operations, which is a detrimental phenomenon leading to flow instabilities, pressure fluctuations, and reduced performance. A time-resolved non-intrusive three-dimensional (3D) flow visualization method is developed for investigating complex vortex structures in centrifugal pumps based on Omega vortex identification and tomographic particle image velocimetry (tomo-PIV). A special-made centrifugal pump prototype was developed with acrylic glass allowing for optical access. This method enables both qualitative and quantitative analysis of high spatiotemporal resolution on flow behaviors and dynamics under various stall conditions. The ultra-high sampling frequency realized over 40 time-consecutive observations per revolution under 0.2 Qd, 0.4 Qd, 0.6 Qd, and 0.8 Qd. It captures the instantaneous evolution of vortex structures that undergoes a growth–breakup transition within 7–9 ms. The rotating stall mechanism is revealed experimentally from the evolution of the vortex structure. Our analysis shows the tomo-PIV's additional velocity component aids in understanding the 3D characteristics of the stall. A substantial region of reverse flow in the z-axis direction is observed under 0.2 Qd. Vortex structures are more prone to blockage at the impeller inlet, exacerbating the stall phenomenon. As the flow rate increases, the velocity distributions across different layers exhibit a laminar characteristic with a more uniform profile. The vortex structures extend radially and migrate toward the outlet. The evolutions of the stall vortex, wake vortex, and inlet vortex share the same dominant frequency components (4.75fn and 5.25fn), but the flow rate affects the proportion of different frequency components.

Active Cluster Wake Mixing

In recent years, the relevance of the interaction between neighboring wind farms has grown steadily. As one farm extracts energy from the wind, a downstream one can systematically experience lower wind speeds which threatens the economic viability of the farm. Significant progress has been made in understanding these farm-farm wake interactions, but we still lack methodologies to mitigate their undesired effects. In this study, we introduce Active Cluster Wake Mixing (ACWM). This novel method aims to accelerate the recovery of the cluster wake using dynamic control actions: By exciting the thrust of the individual turbines depending on their relative location, we generate non-uniform patterns of energy extraction. Phase offsets between the individual excitation signals propagate these regions through the wind farm. This results in large-scale velocity gradients inside the farm, which also affect the flow in the cluster wake region. An in-depth exploration and optimization of ACWM requires significant computational effort. Therefore, we compare three different wind farm modeling approaches in Large Eddy Simulations (LES) that differ in their computational costs regarding their suitability for further exploration of ACWM. For this purpose, we use an unoptimized ACWM scheme with two different excitation frequencies. For the first time ever we successfully show that ACWM manipulates the flow inside the wind farm with favorable effects on the wake velocity. We also demonstrate that the modeling of cluster wakes is challenging and has a significant effect on the potential gain.

A Prefire Approach for Probabilistic Assessments of Postfire Debris‐Flow Inundation

AbstractIncreases in wildfire activity and rainfall intensification are driving more postfire debris flows (PFDF) in many regions around the world. PFDFs are most common in the first postfire year and may even occur before a fire is fully controlled. This underscores the importance of assessing postfire hazards before a fire starts. Evaluation of PFDF hazards prior to fire can help strategize interventions lessening the negative effects of future fires. However, debris‐flow runout and inundation analyses are not routine in PFDF hazard assessments, partially due to time constraints and substantial uncertainties in boundary conditions. Here, we propose a prefire PFDF inundation assessment framework using a debris‐flow runout model based on the Herschel‐Bulkley (HB) rheology (HEC‐RAS v6.1). We constrain model inputs and parameters using Bayesian posterior analysis, rainfall‐runoff simulations, and a debris‐flow volume model. We use observations from recent PFDF incidents in northern Arizona, USA, to calibrate model components and then apply our prefire inundation assessment framework in a nearby unburned area. Specifically, we (a) identify yield stress as the most influential factor on inundation extent and arrival time in a HB model, (b) establish posterior distributions for model parameters suitable for forward modeling by leveraging uncertainties in field observations, and (c) implement a predictive forward analysis in an area that has not burned recently to evaluate PFDF inundation under several future fire scenarios. This study improves our ability to assess postfire debris‐flow hazards before a fire begins and provides guidance for future applications of single‐phase rheological models when assessing PFDF hazards.

U-Pb detrital zircon age determination and provenance of the lower Karoo succession from the Karoo Research Initiative (KARIN) borehole KWV-1, Eastern Cape Province, South Africa

Abstract In recent years, the maximum age of sedimentation and possible sources of detritus to the sedimentary successions of the Karoo Supergroup has received a lot of interest, with various authors presenting age data from across the main Karoo Basin (MKB). Our paper aims to contribute to this ever-growing geochronological database as we report weighted mean ages for the youngest zircons as well as detrital zircon age distributions for the lower Karoo Supergroup succession sampled from the Centre of Excellence for Integrated Mineral and Energy Resource Analysis (CIMERA)-Karoo Research Initiative (KARIN) drill core KWV-1. A total of 880 near concordant zircon ages were determined using Laser Ablation Quadrupole Inductively Coupled Plasma Mass Spectrometry (LA-Q-ICP-MS) from fifteen samples representing the Dwyka Group, the Collingham-, Ripon-, Fort Brown- and Waterford formations of the Ecca Group and the Koonap Formation of the Beaufort Group as intersected by this ~2 352 m deep research borehole drilled in the southeastern sector of the basin. The weighted mean ages for the youngest zircons calculated for the formations of the Ecca- and Beaufort groups compares with findings reported by other authors and with the ages reported for tuffaceous layers associated with these units. The weighted mean ages for the youngest zircons of the Dwyka Group reflect the age of the youngest source area and do not aid in constraining the maximum age of deposition. A significant change in detrital zircon age distribution was noted between the Dwyka Group and the overlying formations of the Ecca and Beaufort groups, which we interpret as a change in provenance. The major Meso-to Neoproterozoic detrital zircon age fractions present in the Dwyka Group are attributed to source areas located towards the north and northeast of the MKB, in line with regional ice flow directions. A significant late Carboniferous to Permian detrital zircon age fraction is however observed throughout the formations of the Ecca- and Beaufort groups, with a lesser fraction of older zircon ages. The prevailing youngest age fraction reflects ages associated with magmatic source areas in the Gondwanide Orogeny located towards the south of the MKB at the time of deposition, while the recycling of deformed sedimentary strata of the Cape Supergroup contained in the Cape Fold Belt is considered the source of older detritus. The source of detritus to the MKB remained unchanged during the deposition of the respective formations of the Ecca- and Beaufort groups, despite changes in the depositional environment brough on by regional tectonics.

Epicardial inflow versus myocardial distribution: average regional transmural coronary flow is not enough.

Epicardial inflow versus myocardial distribution: average regional transmural coronary flow is not enough.

Numerical study of particle dispersion in the wake of a static and rotating cylinder at Re = 140 000

In this study, the particle-laden flow in the wake of a static and a rotating cylinder at Reynolds number of 140 000 was investigated using the Reynolds Averaged Navier–Stokes numerical approach. Three turbulence models such as k–ω shear stress transport, Reynolds stress model, and local-correlation transition model (LCTM) were selected to predict the flow topology. Lagrangian approach with one-way coupling was used to track solid spherical particles of different sizes (0.01, 0.1, 2.5, 10, and 50 μm). The study reveals that LCTM is the most accurate to predict the flow topology in both cases. Cylinder's rotation generates different effects on flow structure. It breaks the wake's symmetry and reduces its width, and increases the frequency of vortex shedding and the size of the recirculation zone. Particle transport analysis has revealed that particles' response to the flow depends on their Stokes number and wake flow topology. Particles of 0.01, 0.1, and 2.5 μm distribute in and around vortex cores, while particles of 10 and 50 μm do not penetrate vortex cores. Instead, 10 μm particles accumulate mainly around the periphery of vortices, while 50 μm particles skip the vortex street to the thin shear flow region between vortices to be transported by the mainstream flow. Finally, cylinder rotation reduces the particle spread in the vertical direction and shifts all particle distributions in the cylinder's rotation direction. Analysis of particle dispersion functions showed that cylinder's rotation reduces differences in dispersion extent depending on particle size.

Thermal-hydraulic phenomena and heat removal performance of a passive containment cooling system according to exit loss coefficient

The natural circulation system has been widely studied for use in various applications because of its inherent advantage. However, it has a key weakness called flow instability that makes the system unstable. Through massive previous research, the mechanisms of flow instability were analyzed, but there was an ambiguous aspect related to the effect of experimental parameters on the phenomenon. Particularly, there has been no report on the heat transfer performance of the system when flow instability phenomena were present. In this study, thermal-hydraulic phenomena of a two-phase natural circulation system that functions as a passive containment cooling system (PCCS) was investigated according to experimental parameters, namely, the temperature boundary (120–158 °C) and exit loss coefficient (0–34.5) under atmospheric pressure conditions. The experimental results showed five different flow types in the loop. The flow modes that occurred by the interaction between flashing and boiling were classified by referring to the mass flow rate, void fraction, and visualization data. The system was more unstable when the temperature boundary conditions increased, but it was more stable when the exit loss coefficient increased. These results have only been confirmed in our research. The reason for the results is that the flow conditions are located on the boundary between Density Wave Oscillation I and the stable flow region, and that boundary does not have clear criteria. In addition, comparing the heat transfer performance of a system by heat rate can confirm the effect of flow instability on the thermal performance of the passive cooling system. As a result, the high exit loss coefficient stabilizes the system better than the low case and has similar heat removal performance.

Exact formulas for estimating the area of flow regions in free boundary problems

An effective technique is proposed for obtaining exact formulas for estimating the area of flow regions in two-dimensional fluid flow problems with free boundaries, that allow an exact solution in terms of elliptic functions. The effectiveness of the technique is demonstrated using a specific example of the problem of capillary waves on the surface of a liquid of finite depth. This example is characterized by mirror symmetry of the flow region, but the technique can be generalized to the case of other symmetry of the flow region.

Implications of homogeneous–heterogeneous reactions, Hall current, and dissipative radiative heat transfer on MHD Casson fluid flow over a bi-directional stretching sheet

This consideration highlights a numerical analysis of the unsteady three-dimensional flow of a Casson fluid over a stretching surface extending in its plane considering the effects of Hall current, thermal radiation, homogeneous–heterogeneous reactions, viscous dissipations, and an external magnetic field. The fluid flow in the region is developed due to the stretching of the sheet along the two directions in its plane. Two different species are present in the flow region which are taking part in homogeneous and heterogeneous reactions. Fluid velocity, thermal, and mass transportation are expressed mathematically using a set of nonlinear partial differential equations ( PDEs ) along with suitable boundary conditions. By using the appropriate similarity transformations, these equations ( PDEs ) that reflect the mathematical model are transformed into a set of nonlinear ordinary differential equations ( ODEs ) . The transformed equations ( ODEs ) were further solved numerically utilizing the bvp 4 c solver. The comprehensive study regarding the impacts of flow parameters on velocities, temperature, and concentration is also presented with graphs. It is observed that the thermal boundary layer is enhanced with an increment in the Hall current parameter, magnetic parameter, and thermal radiation. Moreover, with an increase in homogeneous-heterogeneous reaction parameters, mass transportation decreases. The physical quantities such as the coefficient of skin friction and coefficient of heat and mass transfer are also obtained numerically. Moreover, an appropriate agreement is obtained on comparing the current results with previously published results.

Accelerating regional-scale groundwater flow simulations with a hybrid deep neural network model incorporating mixed input types: A case study of the northeast Qatar aquifer

ABSTRACT This study presents the ‘Dual Path CNN-MLP’, a novel hybrid deep neural network (DNN) architecture that merges the strengths of convolutional neural networks (CNNs) and multilayer perceptrons (MLPs) for regional groundwater flow simulations. This model stands out from previous DNN approaches by managing mixed input types, including both imagery and numerical vectors. Such flexibility allows the diverse nature of groundwater data to be efficiently utilized without the need to convert it into a uniform format, which often leads to oversimplification or unnecessary expansion of the dataset. When applied to the northeast Qatar aquifer, the model demonstrates high accuracy in simulating transient groundwater flow fields, benchmarked against the well-established MODFLOW model. The model's efficacy is confirmed through k-fold cross-validation, showing an error margin of less than 12% across all examined locations. The study also examines the model's ability to perform uncertainty analysis using Monte Carlo simulations, finding that it achieves around 1% average absolute percentage error in estimating the mean hydraulic head. Errors are mostly found in areas with significant variations in the hydraulic head. Switching to this ML model from the conventional MODFLOW simulator boosts computational efficiency by about 99%, showcasing its advantage for tasks like uncertainty analysis in repetitive groundwater simulations.