Scale Physical Model Research Articles

Physical Model Study on Discharge over a Dam Due to Landslide Generated Waves

Impulse waves generated by landslides falling into reservoirs may lead to overtopping of a dam and, in turn, to flooding of the downstream area. In the case of an embankment dam, the overtopping may lead to erosion of the downstream slope, ultimately resulting in breaching and complete failure with consequent further hazardous release of water to the downstream area. This research deals with the overtopping process of a dam due to landslide generated waves in a three-dimensional (3D) physical scale model setup. Experiments have been conducted with varying the slide, reservoir, and dam parameters. The primary focus is on investigating the feasibility of employing the steady state weir equation in order to predict the overtopping discharge over a dam crest due to landslide generated waves. Calibration and validation of the coefficient of discharge values for the different dam section are conducted for the specified model setup. Accordingly, a two-step calculation procedure is presented for predicting the overtopping discharge based on the maximum overtopping depth values. Hence, for the fixed setup, which includes a constant slope angle of the landslide surface, a predictive equation for maximum overtopping depth is proposed, based on slide volume, slide release height, still water depth, upstream dam slope angle, and dam height. The relative slide volume and relative still water depth both seem to have a significant effect on the relative overtopping depth.

Modeling Storm Surge Attenuation by an Integrated Nature-Based and Engineered Flood Defense System in the Scheldt Estuary (Belgium)

There is increasing interest in the use of nature-based approaches for mitigation of storm surges along coasts, deltas, and estuaries. However, very few studies have quantified the effectiveness of storm surge height reduction by a real-existing, estuarine-scale, nature-based, and engineered flood defense system, under specific storm surge conditions. Here, we present data and modelling results from a specific storm surge in the Scheldt estuary (Belgium), where a hybrid flood defense system is implemented, consisting of flood control areas, of which some are restored into tidal marsh ecosystems, by use of culvert constructions that allow daily reduced tidal in- and outflow. We present a hindcast simulation of the storm surge of 6 December 2013, using a TELEMAC-3D model of the Scheldt estuary, and model scenarios showing that the hybrid flood defense system resulted in a storm surge height reduction of up to half a meter in the estuary. An important aspect of the work was the implementation of model formulations for calculating flow through culverts of restored marshes. The latter was validated comparing simulated and measured discharges through a physical scale model of a culvert, and through a real-scale culvert of an existing restored marsh during the storm surge.

Study on the fire growth in underground green corridors

Underground green corridors are getting popular worldwide intending to integrate greenery into built environments. Green corridors provide greenery benefits and aesthetic pleasing view. Proper irrigation is necessary to maintain live plants in green walls. Automated irrigation with adequate amounts and proper drainage is vital to avoid overflows and drowning of plants. Due to improper irrigation plants in green walls can die quickly, creating a potential fire risk in underground green corridors. This paper aims at investigating the ignition, fire propagation and smoke propagation in underground green corridors. Numerical simulations with computational fluid dynamics (CFD) and physical scale modeling experiments were performed. The simulation has been completed based on heat release rate (HRR, kW/m2) data obtained from the cone calorimeter experiments for three plant species, namely; Hedera helix, Peperomia obtusifolia and Aglaonema commutatum. CFD simulations were conducted for an underground passage with a green wall. Results showed that a fire does not occur in underground corridors with fresh and live plants. However, fire risk increases gradually with drying out of plants. For dry plants, the surface temperature may reach above 850 °C. The fire spreads rapidly in about 20 s. An experimental study was carried out on a reduced-scale underground green corridor to investigate the fire and smoke propagation. It is observed that in the vertical direction fire spreads up to the ceiling rapidly. However, fire spreads slowly in the horizontal direction along the green wall. The experiments show that when the green wall is ignited, it may tremendously affect the evacuation due to smoke spread along the corridor and fire propagation in the vertical direction. It is recommended to decrease the fire risk in underground corridors with properly maintained green walls, especially in evacuation paths. This work is an initial study towards the analysis of fire and smoke propagation in underground green corridors.

Stepped spillway with pre-aeration by a deflector: flow characteristics

ABSTRACT Stepped spillways aim to dissipate part of the upstream energy during the flow passage by the chute. However, the use of these structures is limited to a restrict range of specific discharges due to the risk of cavitation damage. As the air entrainment into the flow assists the concrete protection against the aforementioned damages, a possible solution by aerators installed along the chute, already disseminated to smooth chutes, is being studied to be used also in stepped spillways. The purpose of the present paper is to characterize a flow over a stepped chute with induced aeration by deflector and air supply by an airtight chamber trough tests conducted on a reduced scale physical model. The main regions observed during the tests are presented and were developed four equations that allow to approximately predict the location of the main regions for a given spillway.

Investigation of thermo-mechanical response of a geothermal pile through a small-scale physical modelling

Energy piles have been used around the world to harvest geothermal energy to heat and cool residential and commercial buildings. In order to design energy geo-structures, thermo-mechanical response of the geothermal pile must be carefully understood. In this paper, a small scale physical model is designed and a series of heating thermal cycles with various vertical mechanical loads are performed. The instrumented pile is installed inside a dry sand bed. Changes in pile head displacement, shaft strains and pile and sand temperatures are monitored using an LVDT, strain gauges and thermocouples, respectively. Prolonged heating cycles, which would continue until boundary temperature changes, would allow the investigation of excessive heat injection when service loads are active on the pile. The thermal response is discussed including confirmation of a temperature influence zone around the pile, the increase in soil temperature, and minimum vertical heat dispersion in the soil. The mechanical response includes plastic settlements when the vertical load passes 20% of ultimate capacity. Plastic settlements have been observed at the half of the capacity reported for the shorter thermal cycles in similar models. The decrease in the capacity indicates a reduction in elastic response of the soil during longer thermal cycles.

Investigating the effectiveness of a fish-protection structure of the reclamation water intake

The study was conducted at the reclamation water intake facility of Tikhovsky hydroelectric complex. We used data from long-term observations and results of laboratory studies on a 1:20 scale physical model of the Zapan fish protection device. The effectiveness of the model was evaluated using simulators of juvenile fish. Increasing the efficiency of the Zapan fish protection facility is achieved by additional placement in the bottom threshold, which directs the bottom flow along with the young fish to the springboard, where there is an airlift in the form of a bubble curtain that lifts the young along the springboard into the fish-receiving holes of permeable shields. Fish protection design and location in the middle of the water stream do not create a backwater due to low resistance and provide protection for young fish. This increases not only the survival rate of young fish, but also the efficiency of reclamation water intakes. A new design of a fish protection structure for reclamation water intakes of the Zapan type was developed, which provides a fish protection effect of 3 groups of young fish formed by their swimming ability, which allowed determining the size of the elements of the fish protection structure.

Analysis of Carbon Monoxide Gas Dilution on Horizontal Tunnel Front using Laboratory Scale Physical Model

Potential hazards that often occur in underground tunnels are dangerous and toxic gases, one of which is carbon monoxide (CO) which can be found in underground tunnels for example as a result of imperfect detonation on work surfaces. CO gas is very poisonous so it can cause death. This study aims to determine the spread of CO gas when diluting with tunnel ventilation in the horizontal front. This research was conducted on a physical model of the laboratory with a ratio of 1:10 compared to the actual tunnel, that is at the cross section of the model in the laboratory 40 cm x 40 cm. The effectiveness of dilution or dilution is indicated by the value of the diffusion coefficient, where the greater the diffusion coefficient, the more diffused the CO gas concentration, so the faster the CO gas concentration decreases. The parameters of the test conditions are the ratio of the duct to face distance (L/D) and the Reynolds number (Re) which shows the variation of air velocity in the tunnel work surface. Test results from the distribution of CO gas showed the influence of the configuration of the forcing duct and exhausting duct distances on the working front to the CO gas dilution. In this study also found the influence of Reynolds numbers on the value of the diffusion coefficient, that the greater the value of Re, the greater the value of E.

The Feel of 13,000 Containers: How Pilots Learn to Navigate Changing Logistical Environments

ABSTRACTThis article analyses how the 2016 expansion of the Panama Canal changed the work of the pilots responsible for navigating massive ships through the chokepoint. For pilots, the expansion meant learning to maneuver Neo-Panamax vessels that dwarfed anything in their experience. The pilot training associated with the expansion reveals a paradox at the heart of a shipping industry that pursues efficiencies through economies of scale and automation. In the confined waters where maritime routes converge, increased ship size and traffic may render a pilot’s embodied capacity to ‘feel’ how ships handle in particular environments more – not less – important. Combining analysis of historical shipping transitions, interviews, and observations at a 1:25 scale physical model training facility where pilots maneuver miniature megaships through a miniature canal, I argue that the Panama Canal Authority's institutional recognition of the importance of ‘feel’ in contemporary interoceanic transit indexes the emergence of a logistical environment that elevates the status of some forms of embodied knowledge, even as it diminishes others.

Performance comparison of two similar pontoons as floating breakwater using a spectral approach based on an experiment in regular waves

This study focuses on the formulation of a spectral approach to obtain the transmission coefficient (Ct ) of floating breakwaters (FB) in irregular waves based on Ct in regular waves. Additionally, it provides a performance comparison of two quite similar rectangular and circular pontoons as FB. It starts with the comparison of Ct and extends to motions in regular waves by experiment. Overall, the rectangular section showed better performance for both Ct and motions. The spectral approach is formulated and validated. A parametric study on the performance of rectangular and circular FBs has been conducted by applying large scale physical modelling. The study shows that the rectangular section has considerably better performance than the circular section in almost all irregular waves. It is concluded that the spectral approach for irregular waves is a comprehensive method. It is also easy for implementation having FB performances in a limited number of regular waves.

A study on the feasibility of a new roof slab insulation system in tropical climatic conditions

A roof slab provides an extra robustness and a cyclonic resistance to the structures due to its self-weight. However, its performance in warm humid conditions is unsatisfactory because of the thermal discomfort in the immediate space beneath. Insulation has been recognized as an effective passive approach to address this issue. Thus, numerous insulation systems have been developed throughout the world. In this study, a system proven to be fruitful in tropical conditions was chosen and its negative aspects were recognized. Then, a new insulation system (a system with discontinuous supporting strips) was developed addressing the key drawbacks, and its thermal performance was compared with the prevailing systems. Prototype testing indicated that the negative effect of the supporting strips on the thermal performance of the system is negligible. Further, it was proven that this system achieves a heat gain reduction of more than 75%. An actual scale physical model proved that the system performs even better than a Calicut-tiled roof with a timber ceiling in thermal aspects. Computer simulations deduced that on a sunny day in tropical conditions, about 20% of the peak cooling load reduction can be achieved by the system. In addition, it was found out that about 5% reduction of life cycle cost was achieved by this technique for a lifespan of 10–50 years. And also, it was proven that the insulated slab performs better than an insulated Calicut tiled roof in terms of Life Cycle Costing.

Geocellular railway drainage systems: Physical and numerical modelling

Abstract The importance of resilient railway infrastructure is paramount when considering the increased likelihood of extreme weather and flash flood events in coming years. One of the main causes of instability of railway tracks is excess water in the trackbed, particularly when it is at or above the interface of the ballast and subgrade. Conventional drainage systems are susceptible to clogging and deterioration. Resilient track drainage systems should therefore have sufficient capacity to allow water to dissipate quickly, but they should also be designed to ensure long-term operation with minimal or easily performed maintenance. This paper presents results from an investigation of a potential new railway drainage system using geocellular components. In the paper, the development of a large scale physical model is described which represents a full scale unit cell of a sleeper-to-sleeper track substructure. The physical model includes ballast and subgrade layers, under-track and lateral drainage systems, rainfall simulation, and instrumentation. Results demonstrate the relative hydraulic response of the drainage system with and without the geocellular components. The paper also describes the development of a numerical model of the track subgrade and drainage system, which was first calibrated and verified using experimental data from the physical model, then extended to study the effect of certain parameters on the hydraulic response of the railway track. Results indicate that the under-track geocellular drainage system offers potential benefits in terms of maintaining a lower water table level within the subgrade as well as in aiding the migration of fines out of the ballast.

Geobag stability for riverbank erosion protection structures: Physical model study

Geotextile, sand filled bags (geobags) are successfully being used to protect riverbanks against repeated erosion attacks. Large scale physical hydraulic model tests have been used to shed light on the incipient motion of the flexible geobags and enabled the review of the design methodology for sizing geobags against current loading. This study finds that the filling percentage has a large influence on the stability of the geobags, and consequently they should have a degree of filling of at least 80%. Additionally, this study found that the stability formula used for geobags should use the thickness as the characteristic diameter rather than the cube root of the volume.

Experimental and Numerical Model Investigations of the Underwater Towing of a Subsea Module

In underwater towing operations, the drag force and vertical offset angle of towropes are important considerations when choosing and setting up towing equipment. The aim of this paper is to study the variation in drag force, vertical offset angle, resistance, and attitude for towing operations with a view to optimizing these operations. An underwater experiment was conducted using a 1:8 scale physical model of a subsea module. A comprehensive series of viscous Computational Fluid Dynamics (CFD) simulations were carried out based on Reynolds-averaged Navier–Stokes equations for uniform velocity towing. The results of the simulation were compared with experimental data and showed good agreement. Numerical results of the vorticity field and streamlines at the towing speeds were presented to analyze the distribution of vortexes and flow patterns. The resistance components were analyzed based on the numerical result. It was found that the lateral direction was a better direction for towing operations because of the smaller drag force, resistance, and offset angle. Similar patterns and locations of streamlines and vortexes were present in both the longitudinal and lateral directions, the total resistance coefficient decreases at a Reynolds number greater than that of a cylinder.

Bed morphodynamics at the intake of a side channel controlled by sill geometry

As part of a general trend towards river management solutions that provide more room for the river, longitudinal training dams (LTDs) have recently been constructed in the inner bend of the Dutch Waal River, replacing groynes. LTDs split the river in a main channel and a bank-connected side channel with a sill at the entrance. In the present study, a physical scale model with mobile bed was used to study morphological patterns and discharge division in the entrance region of such a side channel. Alternative geometric designs of the sill are tested to investigate the controls on the diversion of water and sediment into the side channel. After reaching a morphodynamic equilibrium, two bar features were observed in the side channel under low flow conditions. An inner-bend depositional bar emerged against the LTD, resembling depositional bars observed in sharp river bends. A second bar occurred in the most upstream part of the side channel, next to the sill, induced by divergence of the flow by widening of the channel and an increasing flow depth after the sill, hence defined as a divergence bar. The morphologically most active system in the side channel emerges for the configuration in which the sill height decreases in downstream direction. For such a geometry, the sediment that settles during low flow is largely eroded during high flow, reducing maintenance needs. A qualitative comparison based on a lab experiment mimicking field conditions demonstrates the realism of the experiments.

Air-Floating Characteristics of Large-Diameter Multi-Bucket Foundation for Offshore Wind Turbines

In the present study, as a novel and alternative form of foundation for offshore wind turbines, the air-floating characteristics of a large-diameter multi-bucket foundation (LDMBF) in still water and regular waves are investigated. Following the theory of single degree of freedom (DOF)-damped vibration, the equations of oscillating motion for LDMBF are established. The spring or restoring coefficients in heaving, rolling and pitching motion are modified by a dimensionless parameter ϑ related to air compressibility in every bucket with the ideal air state equation. Combined with the 1/25 scale physical model tests and the numerically simulated prototype models by MOSES, the natural periods, added mass coefficients and damping characteristics of the LDMBF in free oscillations and the response amplitude operator (RAO) have been investigated. The results shown that the added mass coefficients between 1.2 and 1.6 is equal to or larger than the recommended values for ship dynamics. The coefficient 1.2 can be taken as the lower limit 1.2 for a large draft and 1.6 can be taken as the upper limit 1.6 for a small draft. The resonant period and maximum amplitudes for heaving and pitching motions decrease with increasing draft. The amplitudes of heaving and pitching movements decrease to a limited extent with decreasing water depth.

Solusi inovasi dan kemitraan peremajaan konstruksi kapal kayu nelayan 1 GT dan 3 GT berbasis teknologi material jenis kayu cepat tumbuh untuk mendorong industri galangan kapal masyarakat di wilayah pesisir Provinsi Riau

Tujuan utama pengabdian masyarakat adalah penerapan inovasi Teknologi Material Kayu Komposit dengan memanfaatkan material spesies kayu dengan masa panen pendek (fast growing species) di Desa Teluk Nilap, Kecamatan Kubu Babussalam, Kabupaten Rokan Hilir Provinsi Riau diharapkan mampu memberi solusi permasalahan akan kelangkaan bahan material kayu dengan spesifikasi tertentu guna peremajaan kapal nelayan masyarakat 1 GT dan 3 GT guna mendukung keberlanjutan industri galangan kapal di Wilayah Pesisir Provinsi Riau. Metode pendekatan yang diterapkanuntuk pengabdian masyarakat adalah menggabungkan antara teknologi kayu komposit dengan budaya kearifan lokal yang berorientasikan material kapal berbasis kayu. Untuk kemitraan pembuatan model fisik skala penuh (full scale) kapal kayu nelayan ukuran 1 GT dan 3 GT di industri galangan kapal masyarakat milik H. Muhammad Ali Napiah di Desa Teluk Nilap.Hasil utama dari pengabdian kepada masyarakatmembuktikan bahwa penerapan teknologi material kayu komposit menggunakan jenis kayu cepat tumbuh untuk konstruksi kapal nelayan masyarakat ukuran 1 GT dan 3 GT telah diterapkan pada industri galangan kapal kayu.Sinergitas inovasi dan kemitraan diyakini mendorong peningkatan perekonomian masyarakat nelayan di Wilayah Pesisir Provinsi Riau dengan didukung industri galangan kapal mandiri.

Generalized Extreme Value Statistics, Physical Scaling and Forecasts of Oil Production in the Bakken Shale

We aim to replace the current industry-standard empirical forecasts of oil production from hydrofractured horizontal wells in shales with a statistically and physically robust, accurate and precise method of matching historic well performance and predicting well production for up to two more decades. Our Bakken oil forecasting method extends the previous work on predicting fieldwide gas production in the Barnett shale and merges it with our new scaling of oil production in the Bakken. We first divide the existing 14,678 horizontal oil wells in the Bakken into 12 static samples in which reservoir quality and completion technologies are similar. For each sample, we use a purely data-driven non-parametric approach to arrive at an appropriate generalized extreme value (GEV) distribution of oil production from that sample’s dynamic well cohorts with at least 1 , 2 , 3 , ⋯ years on production. From these well cohorts, we stitch together the P 50 , P 10 , and P 90 statistical well prototypes for each sample. These statistical well prototypes are conditioned by well attrition, hydrofracture deterioration, pressure interference, well interference, progress in technology, and so forth. So far, there has been no physical scaling. Now we fit the parameters of our physical scaling model to the statistical well prototypes, and obtain a smooth extrapolation of oil production that is mechanistic, and not just a decline curve. At late times, we add radial inflow from the outside. By calculating the number of potential wells per square mile of each Bakken region (core and noncore), and scheduling future drilling programs, we stack up the extended well prototypes to obtain the plausible forecasts of oil production in the Bakken. We predict that Bakken will ultimately produce 5 billion barrels of oil from the existing wells, with the possible addition of 2 and 6 billion barrels from core and noncore areas, respectively.

Масштабное физическое гидроакустическое моделирование РЛС с синтезированной апертурой малой дальности для БПЛА.

Масштабное физическое гидроакустическое моделирование РЛС с синтезированной апертурой малой дальности для БПЛА.

Applicability of the 1g similitude law to the physical modeling of soil-track interaction

This study aimed to investigate the applicability of the 1g similitude law to the physical modeling of soil-track interaction. Model track experiments were performed using four physically modeled soil-track systems with different geometric scale factors, under three different relative densities of the model ground. Based on the modeling of the model technique, the results of the physical models were compared in terms of the largest physical model scale. The soil-track interaction behaviors showed similar tendencies on the whole, but slight differences were also observed depending on the geometric scale factor. Such differences, however, were not significant compared to the differences in relation to other soil-structure interaction problems. Moreover, considering that the shearing action on the soil-track interface is a large replica of the shearing process in the direct shear tests of the soil, the differences among the physical models were attributed to the specimen size effect observed in the direct shear test of the soil, rather than to the similitude relationships. Therefore, it can be concluded that the 1g similitude law can be applied to the assessment of the soil-track interaction behavior, provided that the mechanical boundary restraint of the shearing action on the soil-track interface is properly accounted for.

Exterior Electric Hatchback Crossover Car Design with Strong, Vicious and Sharp Concept

Identity of design of an electric car is necessary to show electrical technology and added values for consumers. Design of electic cars today, in the meaning of appearance and image, are judged by consumers as wierd and ugly compared to design of internal combustion engine (ICE) cars. The distinguished factor of electric car compared to ICE car is the technology that provides environment friendly and fuel energy crisis solution. Symbols of electric car can actually be build to be an interesting form and shape, such as smart, lightweight, efficient and clean. This research aims to design a small-medium electric car with 4-passenger car for young urban family consumer. The methods are consecutively: kind of car defining, 2D sketching, ergonomic or anthopometrical study, engineering and passenger package study, 3D styling and part design. The concept of form has adapted by keywords: strong, vicious, and sharp. Definition of ergonomic study based on Indonesian people with percentile of 5% women and 95% of men. Definition of engineering package based on Li-ion battery with size of 24 kWh placed under floor and single electric motor package placed on the front with front wheel system. The design result is a small medium crossover car with dimensions of wheelbase of 2500 mm, height of 1534 mm, front overhang of 858 mm and rear overhang of 723 mm. Design character of strong, vicious and sharp are transformed by small sharp headlamp and rear lamp; small grille with LED lines; smooth sculpting line on entire body; deep sculpting line on side body, firm and bold form of front and rear fender. The design outputs are 3D model of exterior, 3D mode; of body parts, 3D animation and physical scale model