Fluid Flow Conditions Research Articles

Creation of aortic regurgitation model on isolated porcine heart and aortic valve-sparing root replacement using a new device for aortic valve cusps positioning

Valve-sparing surgery in ascending aortic and root aneurysms combined with aortic regurgitation (AR) is a relevant and actively developing trend. The ways to improve these operations are the development of new devices to simplify and standardize valve-sparing procedures using animal models and testing in experiment. Objective. To review experimental methods of aortic root aneurysm and AR modeling, as well as devices simplifying aortic valve-sparing root replacement, including a new device for positioning of aortic valve (AV) cusps during valve-sparing root replacement with AV reimplantation (David procedure), which we have developed. Materials and methods. The components of the developed device were manufactured by three-dimensional printing with preliminary modeling in the parametric environment of computer-aided design with the open source code FreeCAD 0.20.1. The possibility of David procedure on the isolated swine aortic root in the experiment using the new device was evaluated. Results. During the experiments we performed aortic root replacement with AV reimplantation on the isolated porcine aortic root. We noted that the developed device provides good exposure of the surgical correction zone and reduces the probability of damage to the aortic root structures, especially to the AV cusps, in the process of reimplantation. The device eliminates the necessity to use assistants during the main stage of intervention, which reduces the probability of operator-associated complications. Conclusion. Standardization and simplification of reimplantation of AV cusps into the vascular graft during aortic root replacement with the help of the device developed by us is achieved by performing trial positioning of AV cusps and hydraulic tests at different positions of the cusps, which simplifies the search for the optimal point of coaptation and allows to keep the found best position of the cusps until their anchoring inside the graft. The directions of further research are improvement of the design of the developed device, experimental studies with evaluation of the result of valve-sparing surgery under conditions of pulsating fluid flow, testing of the technology on large laboratory animals.

Enhancement of Heat Transfer rate using Axially Interrupted Rectangular Fins in Double Pipe Heat Exchanger

The current investigates the thermo-fluid behavior of a double pipe heat exchanger (DPHE) featuring axially interrupted rectangular fins (AIRF) on the annulus part. The inner tube under this study with AIRF represents an interruption of straight longitudinal fins. This modification introduces periodic breaks along the tube's surface, effectively disrupting the boundary layer of the fluid flow. Consequently, it enables a non-continuous fluid passage along the length of the tube, potentially enhancing heat transfer. The experimentation employs standard liquid water, for investigations conducted under varying cold water mass flow rate 0.136 Kg/s to with 0.374 Kg/s keeping hot water at constant flow rate of 0.34 Kg/s with a fin split interval of four different lengths 7mm,27mm,55mm,100mm. A comprehensive investigation of the AIRF arrangements is carried out in contrast to the plain pipe arrangement, concentrating on fluid flow parameters such as Nusselt number (Nu), friction factor, heat transfer rate, and overall performance factor. The findings reveal that heat transfer rates in an annulus equipped with 7mm AIRF exceed those of a plain pipe by 59.31% under similar fluid flow conditions. The Nusselt number shows 1.5 times increase in the 0.007 m AIRF arrangement compared to the plain pipe. Thermal performance factor for 7mm interrupted length of AIRF outperforms other models.

Time-Lapse Live-Cell Imaging Using Fluorescent Protein Sensors in Outflow Pathway Cells Under Fluid Flow Conditions.

The role of shear stress in regulating aqueous humor (AH) outflow and intraocular pressure (IOP) in the trabecular meshwork (TM) and Schlemm's canal (SC) of the eye is an emerging field. Shear stress has been shown to activate mechanosensitive ion channels in TM cells and induce nitric oxide production in SC cells, which can affect outflow resistance and lower IOP. Live-cell imaging using fluorescent protein sensors has provided real-time data to investigate the physiological relationship between fluid flow and shear stress in the outflow pathway cells. The successful application of time-lapse live-cell imaging in primary cultured cells has led to the identification of key cellular and molecular mechanisms involved in regulating AH outflow and IOP, including the role of autophagy and primary cilia as mechanosensors. This chapter presents a detailed protocol for conducting time-lapse live-cell imaging under fluid flow conditions in the outflow pathway cells.

DDPM investigation on centrifugal slurry pump with inlet and sideline configuration retrofit

The inlet and sideline configuration modifications are widely investigated to alter regional particle fluid flow conditions, considering pressure, turbulence and erosion, therefore to improve energy saving and compartment longevity of centrifugal slurry pump. This paper aims to analyse pump hydraulic and erosion characteristics with proposed pump sideline and inlet configuration retrofit by the DDPM method. Specifically, the inlet guide vane number () and angle (), and sidelining vane (SDV) curvature are investigated in quantitative manner. Accordingly, by adjusting inlet vane configuration and placement, a trade-off between wall erosion and hydraulic performance is observed. The sidelining vane (SDV) design is suggested to avoid resultant counter-current flow formulation, therefore, to mitigate turbulence induced erosion in impeller and volute. However, the SDV modification effect on pump hydraulic head and efficiency is found marginal. In general, this study offers realistic guideline for performance improvement and device upgrading of centrifugal slurry pumps.

Exploring spatial beam shaping in laser powder bed fusion: High-fidelity simulation and in-situ monitoring

Laser beam shaping is a novel and relatively unexplored method for controlling the melt pool conditions during metal additive manufacturing (MAM) processes, but even so it still holds good promise for achieving site-specific tailored properties. In this work, a comprehensive numerical and experimental campaign is carried out to explore this subject within metal laser powder bed fusion (LPBF). More specifically, a multiphysics numerical model is implemented for simulating the heat and fluid flow conditions during LPBF of Ti6Al4V using arbitrary circular beam shapes with various power distributions spanning from a pure Gaussian beam to a pure ring beam profile. The model is subsequently coupled with cellular automata to describe the beam shape effects on the microstructure evolution. Model validation is carried out in a two-fold manner. First, we compare the predicted melt pool cross-section with the one from ex-situ single track experiments, and we find a deviation of less than 9 % in melt pool dimensions. Secondly, advanced in-situ X-ray monitoring is carried out to unravel the melt pool dynamics and we find that the predicted morphology closely matches the in-situ X-ray results. Moreover, it is shown that at lower laser power, a bulge of liquid metal forms at the center of the melt pool when employing ring profiles, and this is ascribed to the absence of recoil pressure at the center of the ring beam. Furthermore, increasing the laser power seems to destabilize the melt pool regime, as the central bulge transforms into a liquid metal jet that periodically collapses and breaks up into hot spatter. Based on the results, we believe that our multiphysics modelling methodology, opens up new pathways for predicting how laser beam shaping influences porosity, surface roughness as well as microstructure formation in LPBF processes.

Migration of dissolution front in a fracture network − Implications for weathering of fractured bedrock systems and boulder formation

Fracture networks contribute to the differential weathering of fractured bedrock at multiple scales. The influence of competing fracture networks is discussed in light of hydrogeochemical conditions to predict the dissolution pattern resulting from spheroidal weathering. The investigation of the dimensionless Péclet (Pe) and Damköhler (Da) numbers on a simple case of a dual-scale fracture network and its application to three fracture network weathering reveals the influence of fluid flow and reaction rate conditions on the dissolution patterns.The conceptual model was numerically validated and compared with observations on lateritic nickel deposits in New Caledonia. A fracture network will contribute to boulder development if the associated fluid flow regime reaches a Pe threshold of around 10. On the other hand, predominant diffusion will inhibit the fracture set in favour of a higher permeability fracture network. The Da drives, for its part, the width of the dissolution halo. Owing to the dependency of the fluid flow regime on the fracture network characteristics, scaling laws were established to estimate the size of the boulders at different scales by predicting the fracture contribution as a function of their Pe.

A simple guideline for designing droplet microfluidic chips to achieve an improved single (bio)particle encapsulation rate using a stratified flow-assisted particle ordering method

Encapsulation of a single (bio)particle into individual droplets (referred to as single encapsulation) presents tremendous potential for precise biological and chemical reactions at the single (bio)particle level. Previously demonstrated successful strategies often rely on the use of high flow rates, gel, or viscoelastic materials for initial cell ordering prior to encapsulation into droplets, which could potentially challenge the system's operation. We propose to enhance the single encapsulation rate by using a stratified flow structure to focus and pre-order the (bio)particles before encapsulation. The stratified flow structure is formed using two simple aqueous Newtonian fluids with a viscosity contrast, which together serve as the dispersed phase. The single encapsulation rate is influenced by many parameters, including fluid viscosity contrast, geometric conditions, flow conditions and flow rate ratios, and dimensionless numbers such as the capillary number. This study focuses on investigating the influences of these parameters on the focused stream of the stratified flow, which is key for single encapsulation. The results allow the proposal of a simple guideline that can be adopted to design droplet microfluidic chips with an improved single encapsulation rate demanded by a wide range of applications. The guideline was validated by performing the single encapsulation of mouse embryonic stem cells suspended in a gelatin-methacryloyl solution in individual droplets of phosphate buffer saline, achieving a single encapsulation efficiency of up to 70%.

Robust 3-D Path Following Control Framework for Magnetic Helical Millirobots Subject to Fluid Flow and Input Saturation.

Precise trajectory control is imperative to ensure the safety and efficacy of in vivo therapy employing the magnetic helical millirobots. However, achieving accurate 3-D path following of helical millirobots under fluid flow conditions remains challenging due to the presence of the lumped disturbances, encompassing complex fluid dynamics and input frequency saturation. This study proposes a robust 3-D path following control framework that combines a disturbance observer for perturbation estimation with an adaptive finite-time sliding mode controller for autonomous navigation along the reference trajectories. First, a magnetic helical millirobot's kinematic model based on the 3-D hand position approach is established. Subsequently, a robust smooth differentiator is implemented as an observer to estimate disturbances within a finite time. We then investigate an adaptive finite-time sliding mode controller incorporating an auxiliary system to mitigate the estimated disturbance and achieve precise 3-D path tracking while respecting the input constraints. The adaptive mechanism of this controller ensures fast convergence of the system while alleviating the chattering effects. Finally, we provide a rigorous theoretical analysis of the finite-time stability of the closed-loop system based on the Lyapunov functions. Utilizing a robotically-actuated magnetic manipulation system, experimental results demonstrate the efficacy of the proposed approach in terms of the control accuracy and convergence time.

Emergence of lobed wakes during the sedimentation of spheres in viscoelastic fluids

The motion of rigid particles in complex fluids is ubiquitous in natural and industrial processes. The most popular toy model for understanding the physics of such systems is the settling of a solid sphere in a viscoelastic fluid. There is general agreement that an elastic wake develops downstream of the sphere, causing the breakage of fore-and-aft symmetry, while the flow remains axisymmetric, independent of fluid viscoelasticity and flow conditions. Using a continuum mechanics model, we reveal that axisymmetry holds only for weak viscoelastic flows. Beyond a critical value of the settling velocity, steady, non-axisymmetric disturbances develop peripherally of the rear pole of the sphere, giving rise to a four-lobed fingering instability. The transition from axisymmetric to non-axisymmetric flow fields is characterized by a regular bifurcation and depends solely on the interplay between shear and extensional properties of the viscoelastic fluid under different flow regimes. At higher settling velocities, each lobe tip is split into two new lobes, resembling fractal fingering in interfacial flows. For the first time, we capture an elastic fingering instability under steady-state conditions, and provide the missing information for understanding and predicting such instabilities in the response of viscoelastic fluids and soft media.

Impacts of Stefan Blowing on Thermophoretic Particle Deposition in Sisko Nanofluid Flow Over a Riga Plate with Soret and Dufour Effects

The proposed framework considers the thermosolutal Marangoni convective flow of Sisko [Formula: see text] nanofluid over a Riga surface with the effects of Stefan blowing and thermophoretic particle deposition. The phenomena of mass and heat are discussed in relation to Soret and Dufour impacts. Electrodes and magnets are arranged on a plate to make up the Riga plate. Since the fluid conducts electricity, the Lorentz force upsurges exponentially in the vertical direction. There are numerous possible uses for this study in different disciplines. The design and production of thin films, coatings, and nanostructured materials can be enhanced by knowledge of how nanoparticles settle onto surfaces under various fluid flow conditions. By optimizing fluid flow and particle deposition processes, engineering insights from this work can guide the development of more efficient heat transfer systems, such as heat exchangers and cooling technologies. The nonlinear governing PDEs are converted into nonlinear ODEs using appropriate transformations. The resultant system of highly nonlinear equations can be solved analytically by using the homotopy analysis method (HAM). The significance of factors on the flow, thermal, and concentration fields are thoroughly explained with the use of tables and figures. Higher Marangoni convection parameter in more effective heat and mass transport within the liquid as well as higher induced flows when the Marangoni convection parameter is increased. A more uniform distribution of these properties throughout the liquid is the result of decreasing temperature and concentration profiles.

Neural Networks For Particle Diffusometry In The Presence Of Flow And With Defocused Particles

Diffusion is a natural phenomenon in fluids. Its measurement can be done optically by seeding an otherwise featureless fluid with tracer particles and observing their motion. However, existing algorithms for particle-based diffusion coefficient measurement have multiple failure modes especially when the fluid has a flow or the particles are defocused. We present a method based on Convolutional Neural Networks (CNNs) for predicting diffusion coefficients in the presence of these real-world effects. The CNNs were trained, validated, and tested on crops from four-frame temporally averaged images. The study includes three simulated datasets: Gaussian-shaped particles under no fluid flow condition, Gaussian-shaped particles under an arbitrary flow condition, and defocused particles under no fluid flow condition. The results show that the CNNs have a low Mean Absolute Error (MAE) of 0.12 µm 2 /s between the true and predicted diffusion coefficient values for the dataset with Gaussian-shaped particles under no fluid flow condition. The CNNs have a slightly higher MAE of 0.19 µm^2 /s for Gaussian-shaped particles under arbitrary flow and defocused particles under no fluid flow conditions. The performance of the CNNs was also benchmarked against four conventional algorithms on these simulated datasets. The results show that the conventional algorithms perform better than the CNNs when the particles are assumed to be Gaussian and the fluid has no flow. However, the CNNs outperform conventional methods in the presence of flow or if the particles are defocused. Finally, the outputs of CNNs were compared against the outputs of conventional algorithms on experimental datasets. This provides uncertainty in the range of 0.19 µm^2 /s - 0.47 µm^2 /s, which is slightly larger than the errors obtained from simulated datasets. Hence, the study shows that CNNs can be used to reliably predict diffusion coefficients from complex particle datasets with as little as four frames.

A 3D bioreactor model to study osteocyte differentiation and mechanobiology under perfusion and compressive mechanical loading

Osteocytes perceive and process mechanical stimuli in the lacuno-canalicular network in bone. As a result, they secrete signaling molecules that mediate bone formation and resorption. To date, few three-dimensional (3D) models exist to study the response of mature osteocytes to biophysical stimuli that mimic fluid shear stress and substrate strain in a mineralized, biomimetic bone-like environment. Here we established a biomimetic 3D bone model by utilizing a state-of-art perfusion bioreactor platform where immortomouse/Dmp1-GFP-derived osteoblastic IDG-SW3 cells were differentiated into mature osteocytes. We evaluated proliferation and differentiation properties of the cells on 3D microporous scaffolds of decellularized bone (dBone), poly(L-lactide-co-trimethylene carbonate) lactide (LTMC), and beta-tricalcium phosphate (β-TCP) under physiological fluid flow conditions over 21 days. Osteocyte viability and proliferation were similar on the scaffolds with equal distribution of IDG-SW3 cells on dBone and LTMC scaffolds. After seven days, the differentiation marker alkaline phosphatase (Alpl), dentin matrix acidic phosphoprotein 1 (Dmp1), and sclerostin (Sost) were significantly upregulated in IDG-SW3 cells (p = 0.05) on LTMC scaffolds under fluid flow conditions at 1.7 ml/min, indicating rapid and efficient maturation into osteocytes. Osteocytes responded by inducing the mechanoresponsive genes FBJ osteosarcoma oncogene (Fos) and prostaglandin-endoperoxide synthase 2 (Ptgs2) under perfusion and dynamic compressive loading at 1 Hz with 5 % strain. Together, we successfully created a 3D biomimetic platform as a robust tool to evaluate osteocyte differentiation and mechanobiology in vitro while recapitulating in vivo mechanical cues such as fluid flow within the lacuno-canalicular network. Statement of significanceThis study highlights the importance of creating a three-dimensional (3D) in vitro model to study osteocyte differentiation and mechanobiology, as cellular functions are limited in two-dimensional (2D) models lacking in vivo tissue organization. By using a perfusion bioreactor platform, physiological conditions of fluid flow and compressive loading were mimicked to which osteocytes are exposed in vivo. Microporous poly(L-lactide-co-trimethylene carbonate) lactide (LTMC) scaffolds in 3D are identified as a valuable tool to create a favorable environment for osteocyte differentiation and to enable mechanical stimulation of osteocytes by perfusion and compressive loading. The LTMC platform imitates the mechanical bone environment of osteocytes, allowing the analysis of the interaction with other cell types in bone under in vivo biophysical stimuli.

Simultaneous influence of contact angle, capillary number, and contraction ratio on droplet dynamics in hydrophobic microchannel

In droplet-based microfluidic systems, droplet motion and behavior largely depend on fluid properties, flow conditions, and microchannel geometry. This study presents a model to predict droplet dynamics within a contraction microchannel, considering various factors, such as contact angle (θ), capillary number (Ca), and contraction ratio (C), within defined ranges, through the employment of a three-dimensional numerical simulation method. Droplets may undergo trap, squeeze, or breakup as they traverse the contraction microchannel, contingent upon the aforementioned factors. The transition from trap to squeeze is determined by the critical value of capillary number ( CaI ). Within the squeezed regime, the contact angle influences droplet deformation and velocity within the contraction microchannel. However, when capillary number ( CaII ) in contraction microchannel increases to a specific threshold corresponding to the contraction ratio, the droplet no longer in contact with the wall and becomes independent of the contact angle, a phenomenon referred to as detachment. Moreover, the contact angle’s impact on the transition of droplets from squeeze to breakup is contingent upon the contraction ratio. This study provides a comprehensive overview of droplet behavior within microfluidic systems, offering valuable insights for the optimization and design of microsystems.

Sustainable Fishing Livelihoods: Exploring the Potential of Sail Technology Using Computational Fluid Dynamic in Traditional Fishing Boats

The potential of using sails and Computational Fluid Dynamics (CFD) to improve the sustainability of traditional fishing boats in the Maluku region. This study highlights the importance of cost-effectiveness and environmental sustainability in the fishing industry. This study shows that Computational Fluid Dynamics (CFD) is effective in simulating the thrust force generated by sails. Sails were used to generate thrust forces on conventional fishing vessels by implementing CFD methodology with three different models. Various sail shapes were incorporated into the modelling process to assess their impact on the thrust force. Subsequently, a comprehensive analysis was conducted to evaluate the sail thrust force under typical operating conditions, focusing specifically on the average speed of the vessel at 15 knots in the waters surrounding the Maluku Islands. The results reveal that sail model 1 has the highest thrust force, amounting to 240.2 N. Sail models 3 and 2 generate thrust forces of 238.9 N and 227.9 N, respectively. The fluid flow conditions around sail model 1 and screen model 2 provide valuable insights into how the sail interacts with the fluid environment to produce thrust. By understanding and optimizing these fluid dynamics, designers and engineers can enhance the performance of sail models and improve their efficiency in harnessing wind power for propulsion. This study highlights the importance of ship science and technology in the design of appropriate propulsion systems for traditional fishing vessels.

Scaling laws for optimized power-law fluid flow in self-similar tree-like branching networks

The power-law fluid flow in tree-like self-similar branching networks is prevalent throughout the natural world and also finds numerous applications in technology such as oil recovery and microfluidic devices. We investigate analysis of optimal power-law fluid flow conditions and the optimal structures within tree-like branching networks, focusing on maximizing flow conductance under the constraint of the network tube’s volume and the surface area. The study considered fully developed laminar power-law fluid flow regimes without considering any losses in the network system. A key observation was the sensitivity of the dimensionless effective flow conductance to the network’s geometrical parameters. We found that the maximum flow conductance occurs when a dimensionless radius ratio β∗ satisfies the equation β∗=N−1/3 and β∗=N−(n+1)/(3n+2) under constrained tube-volume and surface-area, respectively. Here, N represents the bifurcation number of branches splitting at each junction, and n is the fluid power-law index. We further find that this optimal condition occurs when pressure drops are equipartition across each branching level. We validated our results with various experimental results and theories under limiting conditions. Further, Hess–Murray’s law is justified and extended for the shear-thinning and shear-thickening fluid flows for an arbitrary number of branches N. Further, in this study, we also derive the relationships between the geometrical and flow characteristics of the parent and daughter tubes as well as the generalized scaling laws at the optimal conditions for the other essential parameters such as tube-wall stresses, length ratios, mean velocities, tube-volume, and surface-area of the tube distributing within the networks. We find that the fluid power-law index n does not influence the constrained tube-volume scaling at the optimal conditions; however, the scaling laws vary with n under the constrained tube’s surface area. These findings offer valuable design principles for developing efficient transport and flow systems.

Development and application of wellbore flow assurance monitoring system for combustible ice production in deepwater

The commercial development of combustible ice, as the most promising strategy energy, requires not only efficient gas production technology but also a safe flow assurance system. For the depressurization development of combustible ice in the sea area, the issues of wellbore fluid carrying sand, hydrate re-formation in the wellbore, and instability of wellbore flow, are the key problems leading to flow obstacles in the wellbore and affecting the normal production. Therefore, some measures must be taken to effectively monitor and analyze the flow situation in the wellbore during the development of combustible ice in the sea. In this paper, a Wellbore Flow Assurance Monitoring System (WFAMS) is developed to display the fluid flow conditions in the wellbore in real-time during the gas hydrate production, including temperature, pressure, flow rate, the carrying sand amount, etc. Furthermore, the system is capable of online monitoring for potential plug risks, including sand plugs and hydrate blockages caused by gas hydrate formation, as well as assessing flow stability. Additionally, it can provide valuable information, such as production adjustment data and the required injection dosage of thermodynamic inhibitors to prevent hydrate formation. In the 2020 South China Sea production test, this system was used for depressurization production and successfully predicted wellbore flow conditions. This enabled field engineers to monitor flow risks and adjust production plans in a timely manner, ensuring smooth test progress.

Geometric influence of width ratio and contraction ratio on droplet dynamics in microchannel using a 3D numerical simulation

AbstractMicrochannel geometry is an important factor in determining droplet dynamics in droplet‐based microfluidic systems, much like fluid properties and flow conditions. In this context, two important geometric parameters—the contraction ratio () and the width ratio ()—that are limited to particular value ranges are taken into consideration for evaluation. These parameters interact with the capillary number () and viscosity ratio () to affect different aspects of droplet migration and manipulation, such as trap and squeeze regimes. A theoretical model is proposed, and a three‐dimensional numerical simulation method is used in this work. This model predicts the change from trap to squeeze, which is caused by the interaction of the previously mentioned variables. Interestingly, an inverse correlation exists between the width ratio and the critical capillary number for this transition, which is determined as . Furthermore, the investigation explores the droplet elongation and velocity ratio during their passage through the microchannel. By matching input parameters with microchannel geometry, this information may be useful for the design of microfluidic systems, which would facilitate the careful control and manipulation of droplets.

Impinging Flow Mediates Vascular Endothelial Cell Injury through the PKCα/ERK/PPARγ Pathway in vitro

Introduction: This study aimed to elucidate the mechanisms underlying endothelial injury in the context of intracranial aneurysm formation and development, which are associated with vascular endothelial injury caused by hemodynamic abnormalities. Specifically, we focus on the involvement of PKCα, an intracellular signaling transmitter closely linked to vascular diseases, and its role in activating MAPK. Additionally, we investigate the protective effects of PPARγ, a vasculoprotective factor known to attenuate vascular injury by mitigating the inflammatory response in the vessel wall. Methods: The study employs a modified T-chamber to replicate fluid flow conditions at the artery bifurcation, allowing us to assess wall shear stress effects on human umbilical vein endothelial cells in vitro. Through experimental manipulations involving PKCα knockdown and Ca2+ and MAPK inhibitors, we evaluated the phosphorylation status of PKCα, NF-κB, ERK5, ERK1/2, JNK1/2/3, and P38, as well as the expression levels of PPARγ, NF-κB, and MMP2 via Western blot analysis. The cellular localization of phosphorylated NF-κB was determined using immunofluorescence. Results: Our results showed that impinging flow resulted in the activation of PKCα, followed by the phosphorylation of ERK5, ERK1/2, and JNK1/2/3, leading to a decrease in PPARγ expression, an increase in the expression of NF-κB and MMP2, and the induction of apoptotic injury. Inhibition of PKCα activation or knockdown of PKCα using shRNA leads to a suppression of ERK5, ERK1/2, JNK1/2/3, and P38 phosphorylation, an elevation in PPARγ expression, and a reduction in NF-κB and MMP2 expression, alleviated apoptotic injury. Furthermore, we observe that the regulation of PPARγ, NF-κB, and MMP2 expression is influenced by ERK5 and ERK1/2 phosphorylation, and activation of PPARγ effectively counteracts the elevated expression of NF-κB and MMP2. Conclusion: Our findings suggest that the PKCα/ERK/PPARγ pathway plays a crucial role in mediating endothelial injury under conditions of impinging flow, with potential implications for vascular diseases and intracranial aneurysm development.

A Compressible Formulation of the One-Fluid Model for Two-Phase Flows

In this paper, we introduce a compressible formulation for dealing with 2D/3D compressible interfacial flows. It integrates a monolithic solver to achieve robust velocity–pressure coupling, ensuring precision and stability across diverse fluid flow conditions, including incompressible and compressible single-phase and two-phase flows. Validation of the model is conducted through various test scenarios, including Sod’s shock tube problem, isothermal viscous two-phase flows without capillary effects, and the impact of drops on viscous liquid films. The results highlight the ability of the scheme to handle compressible flow situations with capillary effects, which are important in computational fluid dynamics (CFD).

Performance and Formula Optimization of Graphene-Modified Tungsten Carbide Coating to Improve Adaptability to High-Speed Fluid Flow in Wellbore

In order to improve the erosion resistance of steel PDC (Polycrystalline Diamond Compact) bit under high-speed fluid flow conditions underground, it is necessary to develop a high-performance erosion-resistant coating. In this paper, laser cladding was used to prepare the new coating by modifying tungsten carbide with graphene. And the effects of tungsten carbide content and graphene content on the coating performance have been thoroughly studied and analyzed to obtain the optimal covering layer. The research results indicate that, for new coatings, 60% tungsten carbide and 0.3% graphene are the optimal ratios. After adding tungsten carbide, the hardness has significantly improved. However, when the tungsten carbide content further increases more than 30%, the increase in hardness is limited. In addition, when the content of graphene is more than 0.3%, the branched structure becomes thicker. In detail, this is a phenomenon where the segregation of Cr, Si, and W becomes very obvious again, and the segregation of Fe occurs at the Ni enrichment site. The research results contribute to the development and optimization of high-quality erosion-resistant coatings under the high-speed flow conditions in wellbore. These are of great significance for improving the efficiency of oil and gas exploration and development.