Physical Model Study Research Articles

Effects of solitary wave breaking on the hydrodynamic performance of a submerged horizontal plate: A physical modeling study

A series of physical model tests were conducted to investigate the solitary wave control performance of a submerged horizontal plate (SHP). Hydrodynamic coefficients were analyzed for a wide range of SHP specifications, placement conditions, and dimensionless factors. Three wave breaking types on the SHP were identified: non-breaking, collapsing breaker, and plunging breaker. Their correlation with modified wave breaking classification parameters and dimensionless factors was investigated. Indirect reflected waves resulting from backflow were found to take precedence over direct reflected waves generated by the fluid resistance of the SHP. The dissipation coefficient increased as the friction and shoaling effects of the SHP, along with the nonlinearity of the solitary wave, grew more pronounced. The indirect reflection coefficient and the transmission coefficient exhibited an inverse relationship. The reflection coefficient achieved its peak value, while the transmission coefficient attained its minimum value within specific ranges. Based on the modified parameters, the hydrodynamic coefficients exhibited similar distributions. The modified surf-similarity parameter was found to be more suitable for classifying wave breaking types and predicting dissipation coefficients than the other two parameters. These experimental results can be utilized as foundational data for the optimal design of SHPs in controlling solitary waves.

Craniofacial phenotyping with fetal MRI: a feasibility study of 3D visualisation, segmentation, surface-rendered and physical models

This study explores the potential of 3D Slice-to-Volume Registration (SVR) motion-corrected fetal MRI for craniofacial assessment, traditionally used only for fetal brain analysis. In addition, we present the first description of an automated pipeline based on 3D Attention UNet trained for 3D fetal MRI craniofacial segmentation, followed by surface refinement. Results of 3D printing of selected models are also presented.Qualitative analysis of multiplanar volumes, based on the SVR output and surface segmentations outputs, were assessed with computer and printed models, using standardised protocols that we developed for evaluating image quality and visibility of diagnostic craniofacial features. A test set of 25, postnatally confirmed, Trisomy 21 fetal cases (24–36 weeks gestational age), revealed that 3D reconstructed T2 SVR images provided 66–100% visibility of relevant craniofacial and head structures in the SVR output, and 20–100% and 60–90% anatomical visibility was seen for the baseline and refined 3D computer surface model outputs respectively. Furthermore, 12 of 25 cases, 48%, of refined surface models demonstrated good or excellent overall quality with a further 9 cases, 36%, demonstrating moderate quality to include facial, scalp and external ears. Additional 3D printing of 12 physical real-size models (20–36 weeks gestational age) revealed good/excellent overall quality in all cases and distinguishable features between healthy control cases and cases with confirmed anomalies, with only minor manual adjustments required before 3D printing.Despite varying image quality and data heterogeneity, 3D T2w SVR reconstructions and models provided sufficient resolution for the subjective characterisation of subtle craniofacial features. We also contributed a publicly accessible online 3D T2w MRI atlas of the fetal head, validated for accurate representation of normal fetal anatomy.Future research will focus on quantitative analysis, optimizing the pipeline, and exploring diagnostic, counselling, and educational applications in fetal craniofacial assessment.

Physical Modeling Study for Process Optimization of 300-ton RH Vacuum Refining Furnace

Physical Modeling Study for Process Optimization of 300-ton RH Vacuum Refining Furnace

Evaluation of The Effect of Outer Skin Slope on Fire Safety in Double-Skin Façade Systems

In order to increase energy efficiency and user comfort, double skin façade designs are becoming increasingly popular in the built environment as an alternative to traditional façede and curtain walling systems. The vertical cavity between the outer and inner skins of double skin façade systems, which is critical for natural ventilation, can destroy the effectiveness of façade designs by creating fire hazards due to the creation of uninterrupted areas between spaces. It is essential for the sustainability of the buildings to make appropriate fire safety designs for the risks of spreading toxic gases released in a possible fire through the double skin façede cavity to monitor the design before the building is built and to take the necessary precautions. Therefore, that paper developed a numerical model using computational fluid dynamics to monitor the smoke propagation through the cavity of the double skin façade and the temperature changes in the building. As a contribution to the physical modeling studies of double skin façade systems in the literature, the effect of changing the slope of the outer skin on smoke propagation and temperature changes was investigated. A design model was created by developing 9 scenarios: 4 wide angles, 4 acute angles, and a right angle, each with an angle varying by 3 degrees. While acute-angle cavity designs increased the flue effect in the cavity and increased the direction speed and density of the smoke towards the cavity, wide-angle cavity designs reduced the ambient temperature.

Meta‐Study of Carbonate Sediment Delivery Rates to Indo‐Pacific Coral Reef Islands

AbstractCoral reef islands are amongst the most vulnerable environments to sea‐level rise (SLR). Recent physical and numerical modeling studies have demonstrated that overwash processes may enable reef islands to keep up with SLR through island accretion. Sediment supply to these islands from the surrounding reef system is critical in understanding their morphodynamic adjustments, but is poorly constrained due to insufficient knowledge about sediment delivery rates. This paper provides the first estimation of sediment delivery rates to coral reef islands. Analysis of topographic and geochronological data from 28 coral reef islands indicates an average rate of sediment delivery of c. 0.1 m3 m−1 yr−1, but with substantial inter‐island variability. Comparison with carbonate sediment production rates from census‐based studies suggests that this represents one quarter of the amount of sediment produced on the reef platform. Results of this study are useful in future modeling studies for predicting morphodynamic adjustments of coral reef islands to SLR.

The Performance of Flexible Fluid-Structure Interaction Module for Saltmarsh Vegetation Under Flow and Wave Action

This paper evaluates the performance of a new flexible fluid-structure interaction (FSI) module in an open-source computational fluid dynamics (CFD) software - REEF3D - for use in modelling saltmarsh vegetation. Unlike previous studies, which focussed on hydrodynamic response to plants (for example, wave attenuation) to check the accuracy of their numerical modelling efforts, this work attempts to replicate the plants’ drag force and motion behavior, based on results from several physical modelling studies. The flexible FSI module was found to consistently overestimate both the drag and motion of the numerical plants when compared to their physical counterparts. It is hypothesized that this is due to the module’s use of linearly elastic material theory for the flexible structures. This is arguably inadequate for the relatively flexible materials of saltmarsh vegetation.

Integration and learning: a case study of the international higher physical education talent-cultivation model

IntroductionThis study delves into the multifaceted components of talent-training models within China’s physical education domain through Sino-foreign cooperative initiatives. Employing a mixed-methods approach, it systematically evaluates the innovative systems developed by pilot units and outlines their experiential insights.MethodsUsing a mixed-methods approach, this research extensively evaluates the situation of pilot units by collecting and analyzing data from closed-ended and open-ended questionnaires as well as interview responses. The study categorizes and analyzes the data to comprehensively understand cooperative talent-training models.ResultsThe findings are classified into three main themes: Learning, Integration, and Binary Evaluation and Practice Reform. Under the Learning theme, the study observed a selective integration of foreign educational paradigms into the local context, respecting the distinctiveness of Chinese education and aligning with national policies promoting unique educational systems. Additionally, the Integration theme underscores the necessity of meticulously assimilating introduced educational resources into China’s educational fabric, highlighting the need for adaptability when integrating foreign educational elements. Furthermore, the Binary Evaluation and Practice Reform theme reveal the establishment of a dualistic evaluation and reform system tailored to cooperative education specifics, outlining challenges associated with ideological and cultural disparities when integrating certain foreign education aspects into the Chinese context.DiscussionThis research provides insightful exploration into the complexities of collaborative talent-training models in Physical Education. It not only elucidates the assimilation of foreign paradigms but also highlights nuanced challenges and prospects for developing tailored educational systems within specific regional and national contexts.

Model studies for desilting basin for Teesta-VI H.E. project, Sikkim – a case study

Desilting basins play an important role in run-of-river hydro power projects on Himalayan Rivers. These rivers carry huge amount of sediment with them, due to steep slopes and fragile geology of the region. The suspended sediment enters through the power intake and ultimately the power house. This causes heavy damage to the turbines and other under water parts. Therefore, desilting basins are provided to eliminate suspended sediment from the water conductor system. The design of desilting basin is verified on a physical model for 90% removal of suspended sediment coarser than 0.2 or 0.3 mm and efficacy of flushing tunnel below in transporting the settled sediment. Central Water and Power Research Station, Pune has conducted physical model studies for desilting basin for various hydro power projects in India and neighbouring countries. One such study, Hydraulic model studies for desilting basin for 500 MW Teesta-VI Hydro Electric Project, Sikkim is presented in this paper. Various design parameters such as length of desilting basin, length and bed slope of inlet transition, outlet transition, size of silt flushing tunnel, size and spacing of openings connecting main basin with silt flushing tunnel etc. were tested during the model studies. The results in terms of settling efficiency for 0.3 mm size particles were obtained.

Review of crop modelling approaches to address climate change challenges in Africa

Africa is facing an urgent need to increase food production to meet increasing demands. Targeted investments in integrated agriculture and, water management systems are required to meet this challenge. However, there is a lack of comprehensive information on the potential applications of climate-smart agriculture (CSA). This paper reviews current crop modeling technologies and their applications within the scope of climate change and the CSA framework in Africa. It evaluates current research trends in various crop simulation models and suggest advanced approaches to improve crop and environmental assessment, crop management, and decision-making. A total of 140 relevant papers were considered. Results showed that 84% of studies used process-based models, with Maize being the most studied crop. Additionally, DSSAT crop models and analysis of variance models have the highest contribution of physical and empirical crop modeling studies respectively. Over 72% of studies have contributed to adaptation strategies and reducing yield gaps, while only 8% of studies have been conducted on climate change mitigation and their trade-offs with adaptation using crop models under CSA. To ensure food security through sustainable agricultural practices in Africa, there is crucial to implement CSA models with a focus on the climate change mitigation component.

A Study of Population Physical Health Rating Model and Its Correlation Based on Multilevel Constructs

This paper conducts a detailed study on the correlation between residents' dietary and living habits and common chronic diseases. Firstly, the paper constructs and analyzes a multilevel evaluation model for the data in the annex; secondly, it uses the MRMR feature selection model to explore the relationship between age, gender and other factors and residents' living habits and dietary habits; and lastly, it puts forward a series of recommendations for the residents' physical health.

Heavy-tailed distributions of confirmed COVID-19 cases and deaths in spatiotemporal space.

This paper conducts a systematic statistical analysis of the characteristics of the geographical empirical distributions for the numbers of both cumulative and daily confirmed COVID-19 cases and deaths at county, city, and state levels over a time span from January 2020 to June 2022. The mathematical heavy-tailed distributions can be used for fitting the empirical distributions observed in different temporal stages and geographical scales. The estimations of the shape parameter of the tail distributions using the Generalized Pareto Distribution also support the observations of the heavy-tailed distributions. According to the characteristics of the heavy-tailed distributions, the evolution course of the geographical empirical distributions can be divided into three distinct phases, namely the power-law phase, the lognormal phase I, and the lognormal phase II. These three phases could serve as an indicator of the severity degree of the COVID-19 pandemic within an area. The empirical results suggest important intrinsic dynamics of a human infectious virus spread in the human interconnected physical complex network. The findings extend previous empirical studies and could provide more strict constraints for current mathematical and physical modeling studies, such as the SIR model and its variants based on the theory of complex networks.

A Carbon Nanocomposite Material Used in the Physical Modelling of the Overburden Subsidence Process.

Carbon nanomaterial is widely used in structural health monitoring due to the advantage of sensitivity and good mechanical properties. This study presents a novel approach employing carbon nanocomposite materials (CNMs) to characterize deformation and damage evolution in physical modelling. As the primary measurement method, the CNM is used to investigate the deformation characteristics of a 200-400 m thick sandstone bed at a 1 km deep longwall mine. The sandstone unit is identified as an ultra-thick key stratum (UTKS), with its thicknesses varying across different mining panels of the UTKS. The results of CNM monitoring show that the UTKS remains stable even after a consecutive excavation of 900 m in width. This stability impedes the upward propagation of overlying strata failure, leading to minimal surface subsidence. The study demonstrates the huge potential of CNM in the mining area, which can be useful for investigating material damage in physical modelling studies. The findings suggest that the cumulative extraction width in individual mining areas of the mine should be controlled to avoid a sudden collapse of the UTKS, and that special attention should be paid to where the UTKS's thickness changes substantially. The substantial variation in UTKS thickness significantly impacts the pattern of overburden subsidence.

Physical modelling of subsea structure removal via thermally induced pore pressure

Given the requirements of environmental agencies, the decommissioning of subsea structures, including removal, recycling, restructuring or re-adaptation, is inherent to deepwater oil exploration activities. During removal by lifting, the possible development of negative excess pore pressure (i.e., suction) in the soil beneath the structure significantly hampers the recovery of subsea infrastructure. This study presents a method for potentially reducing this suction by heating the fine soil under the foundation during uplift to produce excess thermally-induced positive pore pressure, which may reduce or eliminate suction. Reduced-scale physical modelling studies of mudmat/skirted like foundation structures showed that the negative pore pressure generated during pullout was in certain amount counterbalanced by the thermally-induced positive pore pressure, facilitating their removal. However, this process depends on the magnitude of the sustained loading with respect to the pullout resistance. Upward displacements take place just after heating, without further load increments and the displacement rate is dependent on the level of sustained load.

Physical Model Study on Brittle Failure of Pressurized Deep Tunnel with Support System

Physical Model Study on Brittle Failure of Pressurized Deep Tunnel with Support System

Hydrodynamic Response of Mocean Wave Energy Converter in Extreme Waves

The design of moored floating wave energy converters (WECs) must take into account extreme responses and mooring line loads in order to ensure their survival and continued wave power generation in the ocean environment. This study focuses on Mocean Energy's hinged raft WEC and aims to provide a comprehensive understanding of its hydrodynamic characteristics in survival wave conditions. To achieve this, a physical model study was conducted on a Froude scale of 1 in 50 at the FloWave Ocean Energy Research Facility, University of Edinburgh.
 The experiments involved the use of NewWaves focusing of crest and trough at the model hinge location, as well as long irregular waves. Motion responses of the fore and aft bodies of the WEC were measured using a Qualisys camera, and single component load cells were used to measure the forces in the 3-point catenary mooring line. The hydrodynamic characteristics of the WEC were evaluated in terms of response amplitude operators and non-dimensional mooring line loads.
 Results indicate that the fore and aft bodies of the WEC exhibit similar motion responses, except for the pitch motion. The aft body has a pitch response 2 to 3 times higher than the fore body. Concerning the moorings, the wave load on the mooring line in line with the wave direction was found to be higher than the other two mooring lines which were arranged at an angle to the wave direction.
 In this paper, a brief discussion of the model set-up, parameters, test procedure, analysis of results, and discussion will be reported. The results will provide insight into the behaviour of the Mocean device in survival wave conditions and will aid with the determination of appropriate design parameters for optimal performance and survival in the ocean environment.

NEW INSIGHTS ON USING SCALED MARSH PLANT SURROGATES FOR WAVE ATTENUATION

It has been widely demonstrated in literature that coastal marshes provide positive ecosystem services related to coastal protection, including wave attenuation, storm surge reduction, and erosion prevention (Moller et al., 2014; Wang et al., 2021; Paul and Kerpen, 2021). Physical modelling presents a useful tool for investigating the coastal protection function provided by marsh vegetation in a controlled, repeatable environment, to inform design of nature-based coastal protection strategies, or “nature-based solutions” (NBS). To date, physical modelling studies have been used to investigate the influence of plant biophysical parameters (stem width, stem height, stem flexibility) and hydrodynamic conditions on wave attenuation (e.g., Augustin et al., 2009; Anderson and Smith, 2014; Moller et al., 2014; Ozeren et al., 2014; van Veelen et al., 2020). Such studies have predominantly used surrogate vegetation due to the logistical challenges and facility requirements associated with live plant experiments. Furthermore, most studies have been performed at or near full-scale to reduce uncertainties and scale effects associated with downscaling vegetation, particularly where Reynolds number similarity cannot be preserved (Blackmar et al., 2014). To address existing knowledge gaps related to physical modelling of marsh vegetation at small-scale, experiments were conducted in a 63 m long by 1.22 m wide wave flume at the National Research Council of Canada’s Ocean, Coastal and River Engineering Research Centre, Ottawa, in collaboration with the University of Ottawa and the Institut National de la Recherche Scientifique, Quebec City.

FLEXIBLE FLUID-STRUCTURE INTERACTION OF A FLEXIBLE PLANT MODEL FOR NATURE-BASED SOLUTIONS

Nature-based solutions (NBS) represent a new field of research and engineering applications, becoming increasingly popular in the coastal engineering field. Salt marsh restoration, an example of NBS, is particularly appealing due to the variety of benefits they can provide, especially their capacity to induce sediment accretion, potentially keeping pace with sea-level rise. This study investigates the applicability of the flexible fluid-structure (FSI) interaction module being developed for open-source software REEF3D to the motion of marsh plants under wave action using data from a physical model study performed by Paul et al. (2016). The model consistently overestimates the drag force response of a flexible plastic plant surrogate under wave action. This suggests that this new tool may not be suited for this case. However, further investigation must be performed to test the limits of the model’s application.

DETACHED BREAKWATERS PROTECT LARGE MARINE INFRASTRUCTURE FROM SEVERE STORMS

The port of Richards Bay in south Africa is constantly being subjected to extreme storm events where recorded wave heights exceed 5 m. Over the last decade, these storms have caused significant damage to the port’s breakwater structures, especially to the main southern breakwater. The frequency and intensity of large storms are increasing, and therefore much needed repairs to the aging infrastructure are becoming more frequent. As part of a campaign to enhance the structural integrity of the breakwaters at Richards Bay, the CSIR was contracted to undertake a 3D physical model study, which was completed in 2019. Subsequent to the 2019 study, the CSIR initiated a study to investigate alternative solutions that could potentially be implemented to safeguard marine infrastructure similar to the main breakwater at Richards Bay. This study focused on a submerged detached breakwater constructed in front of the existing main breakwater to shelter it from extreme storm events.

Pseudo-Sections for Target Depth Estimations Using Physical Modelling Studies in Resistivity Prospecting

Pseudo-Sections for Target Depth Estimations Using Physical Modelling Studies in Resistivity Prospecting

Ultrasonic modeling of synthetic finely layered and porous rocks: Theoretical and experimental investigation

The study of porous layered rocks is important in Earth science. Although these media can be found in almost any geological scenario, there have been few physical modeling studies (due in significant part to the difficulty in construction and elaboration) of layered media with porous and permeable layers, even though they closely resemble natural geological environments. In this study, we propose a new way for producing porous/permeable synthetic layered media to provide information about their behavior in the context of seismic wave propagation research. An experimental ultrasonic study is carried out in synthetic porous layered rocks with sequences of two alternate types of isotropic and homogeneous layers with varying physical properties simulating different lithologies. The models are subjected to ultrasonic measurements in order to determine the propagation of P- and S-waves in a transversely isotropic medium with a vertical axis of symmetry (VTI). To measure the temporal P- and S-waveforms, we use transducers with frequencies of 500 kHz and 1 MHz. The velocities were calculated perpendicular and parallel to the bedding planes. The measured velocities are compared to theoretical velocities calculated using Backus averaging and Kennett’s theory. As a result of our construction procedure, pressure-related effects result in significant deviations from theoretical predictions in their measurements, particularly for those with the highest number of layers. We attempt to obtain more uniform sample compaction for this subgroup. The Backus average for 1 MHz (for P and S waves) and Kennett’s hypothesis for 500 kHz (for P waves) represent the experimental results well for the samples with few layers and for the group in which the pressure is controlled.