Article
Nuclear Science & Technology
Mayank Modak, Vishal V. Nirgude, Hyun Sun Park, Yu Jung Choi, Mi Ro Seo
Summary: The coolability of relocated corium from the reactor vessel is a significant safety issue in severe accidents in light water reactors (LWRs). Failure in cooling and stabilizing the molten core can threaten the integrity of the containment boundary. A porous corium debris bed is expected to develop on the bottom of the flooded cavity, and the geometric configuration of the bed is important for accurate coolability assessment.
NUCLEAR ENGINEERING AND DESIGN
(2023)
Article
Nuclear Science & Technology
Yangli Chen, Huimin Zhang, Weimin Ma
Summary: The cornerstone of severe accident strategy of Nordic BWRs is to flood the reactor cavity for the long-term coolability of an ex-vessel debris bed. In this study, the coupling of MELCOR and COCOMO codes was used to analyze the quench process of an ex-vessel debris bed, showing that particle diameter and bed shape have significant effects on the quench front propagation. The coupled simulation predicts earlier cavity pool saturation and containment venting compared to standalone simulation.
ANNALS OF NUCLEAR ENERGY
(2022)
Article
Nuclear Science & Technology
Wanhong Wang, Yangli Chen, Weimin Ma
Summary: In Nordic BWRs, a flooded reactor cavity is used to receive corium in the event of vessel failure, with the aim of forming a coolable debris bed. Previous simulation studies used the MELCOR/COCOMO model for quenching ex-vessel debris beds, but were hindered by the slow computational cost of COCOMO. This study developed a surrogate model (SM) based on artificial neural networks (ANNs) to replace COCOMO, allowing for quick estimations of the quenching process. The coupled MELCOR/SM simulation was then used for integral severe accident analyses, showing similar trends to the MELCOR/COCOMO simulation in predicting containment pressure and pool temperature.
ANNALS OF NUCLEAR ENERGY
(2023)
Article
Mathematics
B. Amaziane, L. Pankratov, A. Piatnitski
Summary: The paper discusses the stochastic homogenization of a system modeling immiscible compressible two-phase flow in random porous media, and successfully proves the convergence of solutions.
JOURNAL OF DIFFERENTIAL EQUATIONS
(2021)
Article
Nuclear Science & Technology
Seyed Mohsen Hoseyni, Walter Villanueva, Sachin Thakre, Alexander Konovalenko, Sevostian Bechta
Summary: This study investigates the dynamics of melt infiltration through a preheated porous debris bed, crucial for severe accident modeling in nuclear power plants. The known analytical model is validated against experimental data, with emphasis on the importance of permeability as the most influential parameter.
ANNALS OF NUCLEAR ENERGY
(2021)
Article
Mechanics
Didier Lasseux, Francisco J. Valdes-Parada
Summary: A closed expression is proposed to calculate the average pressure difference in two-phase flow in porous media. This equation takes into account the pressure gradient, body forces, and interfacial effects in each phase, and is applicable to situations where the fluid-fluid interface is not steady. The accuracy of this expression is validated by comparing it with direct numerical simulations in a model porous structure.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Nuclear Science & Technology
Jong Seok Oh, Sang Mo An, Hwan Yeol Kim, Dong Eok Kim
Summary: This study investigated the pressure drop behavior of air and water flows in porous beds filled with uniform and non-uniform sized spherical particles. The pressure drop data for single-phase flow experiments in uniform particle beds matched well with the original Ergun correlation. The results from two-phase flow experiments were analyzed using numerical models, which relied on sub-models of flow regime transitions and interfacial drag. The experiments revealed the effect of flow regime transition on two-phase pressure drop in uniform particle beds, while the previous models failed to accurately predict counter-current flooding in non-uniform particle beds. A relation between falling liquid velocity and particle bed was proposed to simulate the CCFL phenomenon appropriately.
NUCLEAR ENGINEERING AND TECHNOLOGY
(2023)
Article
Water Resources
Abdullah Aljasmi, Muhammad Sahimi
Summary: Advances in instrumentation have enabled high-resolution imaging of heterogeneous porous media, leading to the feasibility of direct numerical simulation of multiphase flow in two- and three-dimensional images. A bottleneck for image-based simulation is the lengthy computation time, which a new approach aims to overcome by utilizing curvelet transformations for denoising and faster computation. The proposed method demonstrates significant speedup in computational efficiency while maintaining accuracy in simulating multiphase flow in porous media.
ADVANCES IN WATER RESOURCES
(2021)
Article
Mechanics
Graham P. Benham, Mike J. Bickle, Jerome A. Neufeld
Summary: The study examines the effects of horizontally layered heterogeneities on the spreading of two-phase gravity currents in a porous medium and finds that heterogeneities can significantly increase plume migration speed and that uncertainty in field measurements can have a major impact on flow predictions.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Geological
Zheng Chen, Siming He, Wei Shen, Dongpo Wang
Summary: This study investigated the dynamic interaction between debris flow and defense structures through numerical simulation and field investigations. The results show that the shape of debris-flow wakes is correlated with structural parameters, which can help optimize design in debris-flow risk areas.
Article
Mechanics
Jessica Sanchez-Vargas, Francisco J. Valdes-Parada, Mauricio A. Trujillo-Roldan, Didier Lasseux
Summary: A closed macroscopic model for quasi-steady, inertial, incompressible, two-phase generalised Newtonian flow in rigid and homogeneous porous media is derived by upscaling the pore-scale equations. The derived model includes macroscopic equations for mass and momentum balance as well as an expression for the macroscopic pressure difference between the two fluid phases. The predictions from the upscaled models are in excellent agreement with direct numerical simulations, confirming the validity of the derived macroscopic models.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Computer Science, Interdisciplinary Applications
Jisheng Kou, Xiuhua Wang, Shigui Du, Shuyu Sun
Summary: In this paper, we propose a linear and energy stable numerical method for the numerical approximation of a thermodynamically consistent model of two-phase flow in porous media. The proposed method reformulates the model and free energy function, proves the corresponding energy dissipation inequality, and ensures the unique solvability and unconditional energy stability of the numerical solutions. Numerical results demonstrate the performance of the proposed scheme.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Hursanay Fyhn, Santanu Sinha, Alex Hansen
Summary: We studied the effective rheology of immiscible two-phase flow in porous media using a dynamic pore network model. The flow behavior was influenced by the wetting properties of the grains and the capillary forces between them. A percolating regime was observed where zero-capillary force paths enabled flow without a minimum threshold pressure. The relation between the flow rate and pressure drop changed from linear to a power law and then back to linear as the pressure drop increased. The mobility at the percolation threshold was found to be proportional to the difference between the occupation probability and the critical occupation probability raised to a power of about 5.7.
FRONTIERS IN PHYSICS
(2023)
Article
Mechanics
Linlin Fei, Feifei Qin, Jianlin Zhao, Dominique Derome, Jan Carmeliet
Summary: A mesoscopic lattice Boltzmann model is used to simulate isothermal two-component evaporation in porous media. The model incorporates a pseudopotential multiphase model with two components, and employs a cascaded collision operator for improved numerical performance. The model is validated through theoretical analysis and microfluidic experiments. The effects of inflow vapour concentration and contact angle on the evaporation process are investigated, and a scaling formulation for the evaporation rate is proposed.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Xiangyu Li, Liangxing Li, Weimin Ma, Wenjie Wang
Summary: Rapid and accurate identification of two-phase flow patterns in porous media is important for various industries. This study proposes an intelligent recognition method based on feature extraction and support vector machine (SVM) technology. By analyzing the characteristics of pressure signals, models are developed to identify the flow patterns, achieving high accuracy.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Thermodynamics
Cong Li, Jiali Wang, Chenhui Wang, Yanke Jin, Yina Yao, Rui Yang
Summary: This study investigates the impact of NaCl water droplets with various concentrations on a heated surface. The results show that the impact patterns can be categorized into different types, and models are established to predict the spreading behavior of droplets with different concentrations. Additionally, high concentration droplets exhibit more violent boiling and have lower residual energy and rebound time.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
C. Barrera, V. Castro, F. Escudero, J. J. Cruz, I. Verdugo, J. Yon, A. Fuentes
Summary: This study focuses on the characterization of soot maturity and sooting propensity of anisole fuel in a controlled laminar coflow diffusion flame. The results show that the spatial distribution of soot volume fraction is enhanced near the flame centerline, while soot production is promoted near the flame wings. The temperature increase also affects the maturity of soot particles.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Roman W. Morse, Jason Chan, Tiago A. Moreira, Jared J. Valois, Evan T. Hurlburt, Jean-Marie Le Corre, Arganthael Berson, Kristofer M. Dressler, Gregory F. Nellis
Summary: This study investigates the dryout of liquid film and the role of disturbance wave frequency. Experimental results indicate that the heat transfer coefficient associated with optimal boiling conditions is maximized when the surface is dry 5% of the time, independent of pulse amplitude and frequency. Liquid-film measurements, dryout statistics, and direct observation suggest that disturbance-wave frequency can be manipulated by density-wave oscillations in the flow field.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
E. J. Vega, J. M. Montanero
Summary: In this study, we experimentally investigated the bursting of a bubble covered with a surfactant. We found that the bubble bursting time is longer compared to a surfactant-free bubble due to interfacial elasticity. Furthermore, the Marangoni stress drives liquid flow that allows the jet to escape from the end-pinching mechanism within a certain surfactant concentration range.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Guofu Sun, Yi Zhan, Tomio Okawa, Mitsuhiro Aoyagi, Akihiro Uchibori, Yasushi Okano
Summary: Experiments were conducted on liquid jets ejected from oval nozzles to investigate the effects of nozzle orifice shape on jet behavior. The study found that the liquid jet exhibited different characteristics at different liquid flow rates. Correlations were established to predict the liquid jet state and characteristics of the secondary droplets produced during jet impact onto a solid surface. This research extended the available knowledge on liquid jet behavior.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Jeonghoon Lee, Laurent Zimmer, Takeshi Saito, Shinji Nakaya, Mitsuhiro Tsue
Summary: This study investigates the effects of spatial resolution on DMD amplitudes and spatial mode strengths, and proposes scaling factors to correct for the resolution differences. The results show that the proposed scaling factors successfully normalize the amplitudes and spatial modes, allowing for quantitative comparison of data obtained with different spatial resolutions. This study is significant for analyzing spatiotemporal data in various fields.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Yanli Zhao, Shibing Kuang, Xiaoliang Zhang, Mingjun Xu
Summary: This study experimentally investigates the dynamic process of water droplet impacting different wood surfaces and analyzes and discusses the impacting phenomena, phenomena distribution, droplet spreading dynamics, and maximum spread factor. The results show that the impacting process can be distinguished by Weber numbers and Reynolds numbers, and can be predicted by mathematical expressions.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Aakhash Sundaresan, Atul Srivastava, Callum Atkinson
Summary: This study presents the first-ever application of an advanced methodology, combining two-color laser-induced phosphorescence and particle image velocimetry, to investigate the heat transfer mechanisms on the surface of a cylinder placed inside a confined square duct. The technique allows for simultaneous measurement of velocity and temperature fields, reducing the complexity and costs associated with separately measuring temperature distributions. Experimental observations show that increasing the mass flow rate enhances heat removal from the cylinder surface, and increasing the cylinder heat input enhances heat transfer in the rear portion of the cylinder.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Harish K. Patel, Sukhjeet Arora, Rutuja Chavan, Bimlesh Kumar
Summary: This study experimentally analyzed the multiscale statistical assessment of scour depth surrounding spur dikes with downward seepage. The research found that seepage affects the morphological behavior and hydrodynamic characteristics of the channel bed, leading to changes in scour formation. The rate of scour depth changes initially increases with higher seepage velocity but eventually becomes constant over time.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Justas Sereika, Paulius Vilkinis, Gediminas Skarbalius, Algis Dziugys, Nerijus Pedisius
Summary: This study experimentally investigated the pulsatile flow structure based on a transitional-type cavity. It was found that the pulsation amplitude has a more significant effect on the dynamics of recirculation zone than the pulsation frequency. Pulsatile flow can reduce the size of the recirculation zone.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Merav Arogeti, Eran Sher, Tali Bar-Kohany
Summary: This study provides a detailed exploration of the events that occur when a droplet hits a dry solid surface of various small sizes, with a focus on the deposition, receding breakup, and prompt splash phases. By utilizing non-dimensional analysis and graphical representation, the boundaries between different events are defined, and criteria for differentiation based on target-to-drop ratio, Reynolds, and Webber numbers are presented.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Tianxiong Li, Fei Wen, Yingchun Wu, Botong Wen, Lei Wang, Jinxin Guo, Xuecheng Wu
Summary: This study investigates the structure of the flow field induced by a strut in a scramjet and its influence on flame stabilization. Experimental and numerical analyses reveal that the flow field exhibits features beneficial for flame stabilization, but the asymmetry of the flow poses a challenge to flame establishment.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Syed Ehtisham Gillani, Yasir M. Al-Abdeli
Summary: This study investigates the asymmetry in bluff-body stabilised annular jets and finds that swirl can significantly mitigate the asymmetry and restore the symmetry of the jets. Moreover, increasing the Reynolds number and the swirl intensity can both decrease the asymmetry of the jets.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Utsav Bhardwaj, Rabindra Kumar, Shyama Prasad Das
Summary: This study presents an experimental investigation on flooding phenomenon in a pulsating heat pipe (PHP) unit cell, and analyzes the impact of flooding on the performance of PHP. The study recognizes three different flooding mechanisms and finds that currently accepted correlations for predicting flooding velocity are inaccurate. The study emphasizes the need for further research on flooding in PHPs.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Yunpeng Xue, Yongling Zhao, Shuo-Jun Mei, Yuan Chao, Jan Carmeliet
Summary: This study investigates the impact of building morphology on local climate, air quality, and urban microclimate. The researchers conducted an experimental investigation in a large-scale water tunnel, analyzing heat and flow fields using Laser-induced Fluorescence (LIF) and Particle Image Velocimetry (PIV). The findings show that factors such as canyon configuration, buoyant force, and approaching flow magnitude significantly influence fluid flow in street canyons, and the morphology of the street canyon dominates ventilation rate and heat flux. For example, changing the aspect ratio of a street canyon can lead to a significant change in air ventilation rate, ranging from 0.02 to 1.5 under the same flow conditions.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)