Steady-state Conditions Research Articles

Numerical simulation of open channel basaltic lava flow through topographical bends

In this study, we utilised computational fluid dynamics to investigate the behaviour of open-channel basaltic lava flows navigating bends on shield volcanoes. Our focus was on understanding the relationship between flow velocity, rheology, and bend geometry. Employing a simple Force Balance Model (FBM), which considers the equilibrium between hydrostatic pressure and centrifugal force, we accurately approximated the changes in the height of the lava’s free surface through various bend geometries. Our analysis includes examining the influence of channel depth, width, and bend radius on the flow, revealing that variations in these parameters significantly affect the flow’s vertical displacement. Additionally, the bend sector angle emerged as a critical factor, indicating a minimum angle necessary for the flow to fully develop before exiting the bend.Further, we assessed the applicability of the Shallow Water Equations (SWE) for modelling the inertial displacement of the lava flow in bends, finding a good fit. The study extended to comparing the FBM’s predictions of the tilt angle of the flow’s free surface with the SWE results, showing notable agreement under specific conditions, particularly at a bend angle of 90 degrees. The impact of fluid density was also considered, revealing that density is a contributing factor to the development of the wetted line in the bend, a factor that is not captured by the simple FBM model. Finally, we explored different rheologies akin to natural lava flows, such as viscoplastic flow, and determined that factors like yield stress, consistency index, and power law index have a small impact on the flow behaviour in a steady-state condition within a bend.

Comprehensive analysis of thermo-mechanical responses in collapsible soil under varied water content conditions

AbstractIn this research, the effect of both temperature gradients and varied water content on heat transfer in collapsible soil is investigated. The study based on one-dimensional laboratory setup, soil temperature distribution in proximity to a heat source, was examined across four distinct temperatures (ranging from 50 to 200 °C) under varying water content (0%, 10%, 15%, and 20%). Through steady-state conditions and extended measurements over days, data were collected to compare soil thermal conductivity at 10% water content using two different methods. The first method required some of soil characteristics, such as dry density and optimum water content, while the second method relied on heating parameters and supplied heating content. A robust agreement between thermal conductivity values obtained through these two methods was observed. Correlations from experimental data were analyzed to enrich understanding, and multivariate linear regression was employed to predict the thermal conductivity and resistivity of collapsible soils. Results indicated that the higher soil density, the increasing the thermal conductivity, whereas greater soil porosity exhibited the opposite trend. Elevated temperatures were found to enhance soil density, influencing the spatiotemporal distribution of heat within the soil. This research contributes valuable insights into the dynamic behavior of heat transfer in collapsible soil, emphasizing the complex interaction of temperature gradients and water content variations. The findings of this study can advance the development of efficient and sustainable geothermal systems in regions with collapsible soils, potentially enhancing the design and management of structures built on such soils, especially in arid and semi-arid areas.

Piperazine-Based Mixed Solvents for CO2 Capture in Bubble-Column Scrubbers and Regeneration Heat

This work used piperazine (PZ) as a base solvent, blended individually with five amines, which were monoethanolamine (MEA), secondary amines (DIPAs), tertiary amines (TEAs), stereo amines (AMPs), and diethylenetriamine (DETA), to prepare mixed solvents at the desired concentrations as the test solvents. A continuous bubble-column scrubber with one stage (1 s) was first used for the test. Six parameters were selected, including the type of mixed solvent (A), the ratio of mixed solvents (B), the solvent feed rate (C), the gas flow rate (D), the concentration of the mixed solvents (E), and the liquid temperature (F), each one having five levels. Using the Taguchi experimental design, only 25 runs were required. The outcome data, such as the absorption efficiency (EF), the absorption rate (RA), the overall mass-transfer coefficient (KGa), and the absorption factor (φ), could be determined under steady-state conditions. The optimal mixed solvents were found to be A1 (PZ + MEA) and A2 (PZ + DIPA). The parameter importance and optimal conditions for EF, RA, KGa, and ϕ were determined separately; the verification of all optimal conditions was successful. This analysis found that the importance of the parameters was D > C > A > E > B > F, and the gas flow rate (D) was the most important factor. Subsequently, multiple-stage scrubbers were used to capture CO2. Comparing 1 s and 3 s (three-stage scrubber), EF, RA, KGa, and φ increased by 33%, 29%, 22%, and 38%, respectively. The desorption tests for the four optimal scrubbed solutions, including multiple stages, showed that the heat of regeneration for the three scrubbers was 3.57–8.93 GJ/t, in the temperature range of 110–130 °C, while A2 was the best solvent. Finally, the heat regeneration mechanism was also discussed in this work.

Analog One-Cycle Control Strategy for Stable Battery Charging in Photovoltaic Systems

The growing adoption of photovoltaic systems for direct electricity generation from solar radiation has underscored the importance of efficient energy storage solutions. Batteries are the predominant method for storing energy from photovoltaic systems, especially for applications such as electric vehicle (EV) charging. However, these systems face significant challenges, particularly regarding battery longevity, as fluctuations in solar irradiation can lead to harmful voltage spikes. This paper introduces an Analog One-Cycle Control (OCC) strategy designed to mitigate these issues by stabilizing the battery voltage against varying input voltages. The proposed control scheme aims to enhance battery life by preventing damage caused by voltage overshoots. Experimental results demonstrate the effectiveness of the OCC strategy in maintaining steady-state conditions and optimizing power management.

Random Walk Modeling of Conductive Heat Transport in Discontinuous Media

AbstractWe consider heat transport within a discontinuous domain by relying on the modeling approach proposed by Baioni et al. Such approach has been specifically designed to address diffusive processes in media with discontinuous physical properties and generalized boundary conditions at the discontinuities. Three algorithms are here applied to estimate the conductive heat transport in a bimaterial medium. The algorithms undergo testing using two test cases that share the same computational domain but differ in terms of their initial conditions. According to the numerical results all the algorithms ensure the conservation of thermal energy and preserve thermal equilibrium under steady state conditions. The Generalized Uffink Method (GUM) and Generalized HYMLA demonstrate sensitivity to the choice of the time step, whereas the Generalized Skew Brownian Motion appears to be unaffected by the value of $$\Delta t$$ Δ t . The GUM algorithm presents an optimal trade-off between accuracy and computational time.

Energy and Exergy Performance Analysis of Solar-Assisted Thermo-Mechanical Vapor Compression Cooling System

Air conditioning is vital for indoor comfort but traditionally relies on vapor compression systems, which raise electricity demand and carbon emissions. This study presents a novel thermo-mechanical vapor compression system that integrates an ejector with a conventional vapor compression cycle, incorporating a thermally driven second-stage compressor powered by solar energy. The goal is to reduce electricity consumption and enhance sustainability by leveraging renewable energy. A MATLAB® model was developed to analyze the energy and exergy performance using R1234yf refrigerant under steady-state conditions. This study compares four solar collectors—evacuated flat plate (EFPC), evacuated tube (ETC), basic flat plate (FPC), and compound parabolic (CPC) collectors—to identify the optimal configuration based on the collector area and costs. The results show a 31% reduction in mechanical compressor energy use and up to a 44% improvement in the coefficient of performance (COP) compared to conventional systems, with a condenser temperature of 65 °C, a thermal compression ratio of 0.8, and a heat source temperature of 150 °C. The evacuated flat plate collectors performed best, requiring 2 m2/kW of cooling capacity with a maximum exergy efficiency of 15% at 170 °C, while compound parabolic collectors offered the lowest initial costs. Overall, the proposed system shows significant potential for reducing energy costs and carbon emissions, particularly in hot climates.

Thermal-biomechanical manikin applied in turbulent airflow and vibration systems in transient conditions

This paper applied a thermal-biomechanical manikin in turbulent airflow and vibration systems in transient conditions. This numerical model evaluated the thermal and biomechanical components to which the human body is subjected. The first one considers the first-order equations systems based on the thermal numerical model, while the second one considers the second-order equations systems based on the vibration numerical model. This second-order equations system is converted into a first-order equation system. The resolution of the thermal and biomechanical numerical models is made through the Runge-Kutta-Fehlberg method with error control. The thermal numerical model is used in the study of the steady-state and transient conditions when the skin is subjected to mean and turbulent airflow. The biomechanical numerical model is used in the study of the human body vibrations applied to the feet, that a standing person is subjected, using periodical and random vibration signals of the floor. The thermal analysis shows that with an air fluctuation velocity, the skin temperature reduces slightly. The amplitude of the vibration in the lower body section is higher than in the upper body section. The introduction of the randomised vibration, in the periodical vibration, the human body vibration increases the fluctuation level.

Mathematical modeling and experimental analysis of the double-effect DCMD-heat pump integrated system

High energy consumption represents one of the hindrances in enabling large scale application of membrane distillation. In this work, experimental and simulation studies of a double-effect direct-contact membrane distillation integrated with a single-stage vapor-compression heat pump (DE-DCMD-HP) were carried out for concentrating tap water with the aim to evaluate the energy saving of the integrated system. It was found during our experiments that an auxiliary cooler must be added to remove the excess heat from HP to enable the integrated system to reach the steady-state condition. The temperature-heat flux plots were first utilized to analyze how HP and DE-DCMD affected each other and reveal their coupling mechanism. The simulation results showed that the increase in the first-effect feed inlet temperature, Tfi,1 and the flow rate, V caused the thermodynamic cycle line of refrigerant shift to higher temperature, which led to the increase of the input power of the compressor and the auxiliary cooler, ultimately affecting the water production mass rate, ṁd, the coefficient of performance, COP, the gain output ratio, GOR, and the specific energy consumption, SEC. The experimental and simulation results revealed that increasing Tfi,1 and V increased the permeate flux Nh and GOR and reduced the SEC. The performances for three different DCMD configurations were furthermore evaluated via experiments at constant feed temperature whereby the SEC decreased from 2168 kWh·t−1 for single-effect DCMD to 1085 kWh·t−1 for DE-DCMD to 257 kWh·t−1 for DE-DCMD-HP.

Unsteady Upwind Aerodynamics of a Sailing Yacht

_ Sail aerodynamics has been a researched topic since the start of competitive racing, such as the America's Cup and Whitbread Round the World Race. Recently, with restrictions on the use of wind tunnels and towing tanks in the America's Cup, there has been an increase in computational fluid dynamics (CFD) to study the aerodynamics and performance of yacht sails. These studies typically model steady-state conditions, but in contrast, this paper demonstrates the implementation of dynamic wind conditions in Reynolds Averaged Navier Stokes CFD and the effects it has on the aerodynamics of a yacht sailing upwind. A user-defined function was used to give a velocity profile and vary the wind direction with time to simulate a gust condition with a period of 10 s. In addition to the gusting model, steady models were run for the apparent wind angles (AWA) experienced in the gust to see if the dynamic wind conditions could be modelled by a series of steady state snapshots. The results show minor differences in the streamlines of two models and the pressure distributions show no significant difference. There is only a slight difference in sail forces at high AWAs. Although further research would be required this information could be valuable to anyone using CFD to test sail designs. Keywords CFD; transient; steady; upwind; UDF; RANS

Oxygen extraction fraction mapping based combining quantitative susceptibility mapping and quantitative blood oxygenation level-dependent imaging model using multi-delay PCASL

Background and purposeThe oxygen extraction fraction is an essential biomarker for the assessment of brain metabolism. A recently proposed method combined with quantitative susceptibility mapping and quantitative blood oxygen level-dependent magnitude enables noninvasive mapping of the oxygen extraction fraction. Our study investigated the oxygen extraction fraction mapping variations of single-delay and multi-delay arterial spin-labeling. Materials and methodsA total of twenty healthy participants were enrolled. The multi-echo spoiled gradient-echo, multi-delay arterial spin-labeling, and magnetization-prepared rapid gradient echo sequences were acquired at 3.0 T. The mean oxygen extraction fraction was generated under a single delay time of 1780 ms, multi-delay arterial spin-labeling of transit-corrected cerebral blood flow, and multi-delay arterial spin-labeling of arterial cerebral blood volume. The results were compared via paired t tests and the Wilcoxon test. Linear regression analyses were used to investigate the relationships among the oxygen extraction fraction, cerebral blood flow, and venous cerebral blood volume. ResultsThe oxygen extraction fraction estimate with multi-delay arterial spin-labeling yielded a significantly lower value than that with single-delay arterial spin-labeling. The average values for the whole brain under single-delay arterial spin-labeling, multi-delay arterial spin-labeling of transit-corrected cerebral blood flow, and multi-delay arterial spin-labeling of arterial cerebral blood volume were 41.5 ± 1.7 % (P < 0.05), 41.3 ± 1.9 % (P < 0.001), and 40.9 ± 1.9 % (N = 20), respectively. The oxygen extraction fraction also showed a significant inverse correlation with the venous cerebral blood volume under steady-state conditions when multi-delay arterial spin-labeling was used (r = 0.5834, p = 0.0069). ConclusionThese findings suggest that the oxygen extraction fraction is significantly impacted by the arterial spin-labeling methods used in the quantitative susceptibility mapping plus the quantitative blood oxygen level-dependent model, indicating that the differences should be accounted for when employing oxygen extraction fraction mapping based on this model in diseases.

Role of the Kölliker-Fuse/parabrachial complex in the generation of postinspiratory vagal and sympathetic nerve activities and their recruitment by hypoxemic stimuli in the rat.

In the rat, the activity of laryngeal adductor muscles, the crural diaphragm, and sympathetic vasomotor neurons is entrained to the postinspiratory (post-I) phase of the respiratory cycle, a mechanism thought to enhance cardiorespiratory efficiency. The identity of the central neurons responsible for transmitting respiratory activity to these outputs remains unresolved. Here we explore the contribution of the Kölliker-Fuse/parabrachial nuclei (KF-PBN) in the generation of post-I activity in vagal and sympathetic outputs under steady-state conditions and during acute hypoxemia, a condition that potently recruits post-I activity. In artificially ventilated, vagotomized, and urethane-anesthetized rats, bilateral KF-PBN inhibition by microinjection of the GABAA receptor agonist isoguvacine evoked stereotypical responses on respiratory pattern, characterized by a reduction in phrenic nerve burst amplitude, a modest lengthening of inspiratory time, and an increase in breath-to-breath variability, while post-I vagal nerve activity was abolished and post-I sympathetic nerve activity diminished. During acute hypoxemia, KF-PBN inhibition attenuated tachypneic responses and completely abolished post-I vagal activity while preserving respiratory-sympathetic coupling. Furthermore, KF-PBN inhibition disrupted the decline in respiratory frequency that normally follows resumption of oxygenation. These findings suggest that the KF-PBN is a critical hub for the distribution of post-I activities to vagal and sympathetic outputs and is an important contributor to the dynamic adjustments to respiratory patterns that occur in response to acute hypoxia. Although KF-PBN appears essential for post-I vagal activity, it only partially contributes to post-I sympathetic nerve activity, suggesting the contribution of multiple neural pathways to respiratory-sympathetic coupling.NEW & NOTEWORTHY Inhibition of neurons in the pontine Kölliker-Fuse/parabrachial complex (KF-PBN) differentially inhibited postinspiratory (post-I) activity in vagal and sympathetic outputs. The strong recruitment of post-I vagal activity that occurs in response to hypoxemia is selectively abolished by KF-PBN inhibition. This suggests that 1) post-I activity in vagal and sympathetic outputs may be generated by partially independent mechanisms and 2) neurons in the KF-PBN are a preeminent source of drive for the generation of eupneic post-I activity.

Optimizing the influence of refrigerant superheat on the cooperative thermal management system performance for the vehicle cabin and battery

The refrigerant superheat significantly impacts on the energy consumption of the vehicle cabin and battery collaborative thermal management system. The study investigates the problem using a genetic algorithm. Firstly, the model of collaborative thermal system is established and verified. Then, the coefficient of performance (COP) maximization is taken as the optimization target during steady-state conditions. The results show that the optimal refrigerant superheat at the evaporator outlet (SEva) is very low for different heat dissipation of the battery (HBat) as well as ambient temperature, while the optimal refrigerant superheat at the chiller outlet (SChi) is affected by the HBat as well as ambient temperature. Finally, according to conclusions under the steady state, the SEva is set to 1 K and taking the energy consumption (EC) as the response under transient condition, the SChi is determined. The results indicate that when the SChi is decided by single-point optimization, the optimal SChi is 18 K, and the EC is 1490 kJ, which is 2.3 % energy saving compared to the basic condition. When the SChi is decided by two-point optimization, the optimal two superheats are 12 K and 37 K and the EC is 1460 kJ, which is 4.3 % energy saving compared to the basic condition.

Hemophilia: is arevolution in treatment options taking place?

Prophylactic replacement therapy for hemophiliaA (hereditary factor VIII deficiency) is asuccess story of the production of coagulation factor concentrates from donor plasma. Recombinant factor concentrates, which are also produced with modified gene constructs for coagulation factor VIII in order to improve pharmacological properties, have since proven their worth. This successful development over many years of factor concentrates for the successful treatment of hemophilia patients has now been followed by the innovation of afactor VIII mimetic in the form of amonoclonal antibody, which was developed in Japan already some years back. Emicizumab is ahumanized, bispecific monoclonal antibody for therapeutic use in hemophiliaA. With this therapeutic agent, the treatment of the hereditary coagulation defect is based, for the first time, on acompletely new active principle. The specific antibody simulates the properties of coagulation factor VIII as acofactor for the formation of the tenase complex with the coagulation factors IX and X. As a result under steady state conditions almost normal thrombin and thus fibrin formation can be achieved.

Soluble adenylyl cyclase is an acid-base sensor in rainbow trout red blood cells that regulates intracellular pH and haemoglobin-oxygen binding.

To identify the physiological role of the acid-base sensing enzyme, soluble adenylyl cyclase (sAC), in red blood cells (RBC) of the model teleost fish, rainbow trout. We used: (i) super-resolution microscopy to determine the subcellular location of sAC protein; (ii) live-cell imaging of RBC intracellular pH (pHi) with specific sAC inhibition (KH7 or LRE1) to determine its role in cellular acid-base regulation; (iii) spectrophotometric measurements of haemoglobin-oxygen (Hb-O2) binding in steady-state conditions; and (iv) during simulated arterial-venous transit, to determine the role of sAC in systemic O2 transport. Distinct pools of sAC protein were detected in the RBC cytoplasm, at the plasma membrane and within the nucleus. Inhibition of sAC decreased the setpoint for RBC pHi regulation by ~0.25 pH units compared to controls, and slowed the rates of RBC pHi recovery after an acid-base disturbance. RBC pHi recovery was entirely through the anion exchanger (AE) that was in part regulated by HCO3 --dependent sAC signaling. Inhibition of sAC decreased Hb-O2 affinity during a respiratory acidosis compared to controls and reduced the cooperativity of O2 binding. During invitro simulations of arterial-venous transit, sAC inhibition decreased the amount of O2 that is unloaded by ~11%. sAC represents a novel acid-base sensor in the RBCs of rainbow trout, where it participates in the modulation of RBC pHi and blood O2 transport though the regulation of AE activity. If substantiated in other species, these findings may have broad implications for our understanding of cardiovascular physiology in vertebrates.

Numerical analysis on performance evaluation of photovoltaic thermal systems using ternary hybrid nanofluids and forced convection around copper cylinders

This study evaluates the performance of a photovoltaic thermal (PV/T) system using forced convection and ternary hybrid nanofluids, comprising water with cobalt, zinc, and silver. The PV/T system includes a glass absorber, polycrystalline silicon, and a flow channel with eight copper cylinders, positioned at 20 %, 40 %, 60 %, and 80 % along the channel, both above and below the flow path for optimal thermal conductivity. The working fluid is modeled under turbulent, steady-state conditions using the κ−ε turbulence model.Numerical simulations via COMSOL Multiphysics 6.0 evaluate the system's thermal and fluid dynamics, focusing on local Nusselt numbers and photovoltaic cell thermal efficiency compared to a baseline. The investigation spans Reynolds numbers from 10,000 to 100,000, nanoparticle volume fractions of 1 %–20 %, and aspect ratios of 0.1–0.3. The aspect ratio in this study is defined as the ratio of the height of a square obstacle within the flow channel to the total height of the flow channel. A supervised machine learning framework develops predictive regression models for system analysis. Results show fluid force at the outlet increases by about 1200 % and 1300 % for aspect ratios of 0.1 and 0.3 as the Reynolds number rises. The Nusselt number enhances by 420 % and 466 % at a 20 % nanoparticle volume fraction for aspect ratios of 0.1 and 0.3, respectively, with a 9 % improvement in photovoltaic cell efficiency. This work uniquely applies machine learning to derive regression equations for fluid force, Nusselt number, and electrical efficiency, an approach not previously explored in laminar flow studies.

Design and analysis of a piezo-actuated hydraulic micro-displacement amplifier with high bandwidth and large amplification ratio

Micro-displacement amplifiers show great potential for enhancing the performance of piezoelectric ceramic stacks. However, designing a compact micro-displacement amplifier with a high amplification ratio and broad bandwidth remains challenging. This article introduces a hydraulic micro-displacement amplifier driven by a piezoelectric ceramic stack with a large amplification ratio, high bandwidth, and eliminating parasitic displacement. Theoretical and simulation analyses are performed for the hydraulic micro-displacement amplifier, optimizing parameters such as edge thin ring thickness and spring stiffness. A prototype was fabricated and tested in a series of experiments. The experimental results demonstrate that, under steady-state conditions, the hydraulic micro-displacement amplifier achieves an amplification ratio of 26.12 with a standard deviation of 2.28. The maximum output displacement is 172.4 μm at 150 V, and the resonant frequency is 445 Hz under a 20 N load. This study provides a novel approach to designing micro-displacement amplifiers.

Metabolomics of related C3 and C4 Flaveria species indicate differences in the operation of photorespiration under fluctuating light.

C3 photosynthesis can be complemented with a C4 carbon concentrating mechanism (CCM) to minimize photorespiratory losses. C4 photosynthesis is often more efficient than C3 under steady-state conditions. However, the C4 CCM depends on inter-cellular metabolite concentration gradients, which must increase following increases in light intensity and could decrease rates of C4 photosynthesis under fluctuating light. Additionally, incomplete flux through photorespiration could prove beneficial to C4 assimilation during light induction of the CCM. Here, we compare metabolic profiles in the closely related C3 Flaveria robusta and C4 Flaveria bidentis during a light transient from low to high light to determine if these non-steady state accumulation patterns provide insight to the induction of the metabolite gradients needed to drive C4 intermediate transport and if there is incomplete cycling of photorespiratory intermediates. In these C3 and C4 species, metabolite steady-state pool sizes suggest that C4 transport acids maintain concentration gradients across the bundle sheath and mesophyll cell types under these light fluctuations. However, there was incomplete flux through photorespiration in the C4 F. bidentis, which could reduce photorespiratory CO2 loss via glycine decarboxylation and help maintain higher rates of assimilation during following induction periods.

Optimizing CO2 Capture Efficiency: Harnessing IoT and Industry 4.0 for Precise Temperature Analysis in Packed Absorption Columns

The deployment of various technologies to mitigate climate change is crucial for developing techniques that advance climate action. Climate change is exacerbated by rising levels of carbon dioxide (CO2) and other greenhouse gases, deforestation, and the use of fossil fuels. Urgent measures are needed to enhance CO2 capture efficiency, in alignment with the Sustainable Development Goals (SDGs) and climate action initiatives. This study investigates the influence of temperature variations in a packed absorption column on CO2 capture efficiency. By employing Internet of Things (IoT) and Industry 4.0 principles, it facilitates precise data acquisition to monitor temperature fluctuations during experiments. Comparative evaluations under steady-state and saturation conditions provide critical insights for optimizing CO2 capture in post-combustion processes. Conducting exploratory analyses enhances system understanding and informs design and operational strategies for effective and sustainable CO2 capture. This research delves into the technical aspects of temperature optimization, emphasizing its significance for sustainable practices and the urgency of addressing climate change through innovative, technology-driven solutions.

Physics simulation capabilities of LLMs

Large Language Models (LLMs) can solve some undergraduate-level to graduate-level physics textbook problems and are proficient at coding. Combining these two capabilities could one day enable AI systems to simulate and predict the physical world. We present an evaluation of state-of-the-art (SOTA) LLMs on PhD-level to research-level computational physics problems. We condition LLM generation on the use of well-documented and widely-used packages to elicit coding capabilities in the physics and astrophysics domains. We contribute ∼50 original and challenging problems in celestial mechanics (with REBOUND), stellar physics (with MESA), 1D fluid dynamics (with Dedalus) and non-linear dynamics (with SciPy). Since our problems do not admit unique solutions, we evaluate LLM performance on several soft metrics: counts of lines that contain different types of errors (coding, physics, necessity and sufficiency) as well as a more educational’ Pass-Fail metric focused on capturing the salient physical ingredients of the problem at hand. As expected, today's SOTA LLM (GPT4) zero-shot fails most of our problems, although about 40% of the solutions could plausibly get a passing grade. About 70%–90% of the code lines produced are necessary, sufficient and correct (coding & physics). Physics and coding errors are the most common, with some unnecessary or insufficient lines. We observe significant variations across problem class and difficulty. We identify several failure modes of GPT4 in the computational physics domain, such as poor physical units handling, poor code versioning, tendency to hallucinate plausible sub-modules, lack of physical justification for global run parameters (e.g., simulation time, or upper-lower bounds for parametric exploration) and inability to define steady-state or stopping conditions reliably. Our reconnaissance work provides a snapshot of current computational capabilities in classical physics and points to obvious improvement targets if AI systems are ever to reach a basic level of autonomy in physics simulation capabilities.

Improved sprayed water boiler design for steam production

The lengthy time required for conventional boilers to attain a steady state, their sizable size, the substantial pressure drop, and their high cost are all disadvantages. The objective of this study was to develop a novel design for a boiler to achieve better performance based on a sprayed water boiler (SWB) through injectors with a specific spray rate in a near-atomized form over tubes containing hot gases. As the water temperature in the SWB is equal to the temperature of the water sprayed by the injectors, the temperature difference between the hot gases and the water is higher than in the conventional boiler. A parametric study was conducted to investigate the main parameters affecting the boiler performance, such as the steam quantity and quality, the time required to reach the steady state condition, the size of the boiler, and the drop pressure on the hot-gas side. The results showed that the size of the SWB was significantly smaller than that of a conventional boiler. When generating steam of the same quantity and quality, the size of the SWB is one-third of the conventional size. This reduces the manufacturing costs of the boiler and the pressure drop of the hot gases inside the boiler. It was also found that the thermal efficiency of the SWB was higher, and the start-up time to reach a steady state of operation was less than 1% of the time required for the conventional boiler. To close the gaps in the theoretical design, an experimental test should be performed.