Physical Modeling Method Research Articles

Development, modeling and research of technology for producing longish deformed semi-finished products from aluminum-magnesium alloys with low scandium contents

The paper provides the results of studying the technology for producing longish deformed semi-finished products by sheet rolling and direct rolling-extruding of aluminum-magnesium alloys with different scandium contents. Computer and physical modeling methods were used for the research and the results were verified by pilot tests. These alloys were selected for the research due to the fact that Al–Mg aluminum alloys doped with scandium have increased corrosion resistance along with their high strength. In this regard, this research was aimed to obtain longish deformed semi-finished products in the form of sheet metal, rods and welding wire from economically alloyed Al–Mg alloys. Computer simulation was performed using the DEFORM-3D software package to determine rational conditions of hot rolling of large-sized ingots and deformation modes of the combined processing using the method of direct rolling-extruding of rods made of the investigated alloys. At the same time, the technological and force parameters of these processes were justified with the laws of their change presented. Experimental results obtained made it possible to determine the limit values of force parameters and to study the structure and properties of deformed, annealed and welded semi-finished products made of the investigated alloys during the physical modeling of processes studied. In addition, metal properties were determined in a fairly wide range of changes in temperature, speed, and deformation parameters. Based on the results of experimental studies and modeling, recommendations were given for the industrial development of the technology for hot rolling of thick ingots from the investigated alloys. At the same time, technological solutions, regulations and conditions for deformed semi-finished products made of the investigated alloys were developed and batches of sheet metal with the required level of mechanical and corrosion properties were obtained.

PHYSICAL MODELING OF THE HYDRODYNAMIC PROCESSES OF CASTING MOLDS POURING FILLED WITH A LOCALLY ORIENTED REINFORCING PHASE

In the process of manufacturing reinforced castings by lost foam casting it is important to determine the laws of gas-hydrodynamic processes that occur during mold pouring. The study of liquid metal filling process a mold filled with a locally oriented reinforcing phase was carried out by the method of physical modeling using cold liquids on a special experimental bench that allows superimposing rarefaction to the front of the liquid metal. The video frames of the filling process the mold cavity without the reinforcing phase and with the presence of vertically mounted metal rods are obtained. It was established that the filling process without reinforcing elements occurs in three stages: 1) the flow of a gushing free stream into space; 2) the destruction of the free stream with the capture of the gas phase; 3) filling the form with a continuous stream with the removal of smaller gas inclusions from the liquid volume. It was also established that with an increase in the rarefaction, the character of filling the mold is preserved, only the intervals of existence of the corresponding stages are reduced. In the presence of a reinforcing phase in the cavity, a marked decrease in the height of the gushing of the jet in the initial stage with an increase in the number of installed rods. In addition, crushing by rods of a limited model space creates more favorable conditions for removing the filled gas phase from a moving stream.

The Development and Application of a New Water Control Technology with Fine Segmentation Features

To counter the high water-cut issues in the later production stage of horizontal wells in the western South China Sea, a water control technology that combines inflow control devices and light proppant has been developed. The development of the new technology combined both flow theory analysis and physical modeling methods, to reach a conclusion that the axial flow resistance of a gravel packed screen annulus is much higher than its radial flow resistance, utilizing this conclusion, the inflow control screens can be gravel-packed to balance the production profile along the horizontal wellbore, with a better sand control effect. Comparing to the conventional water control methods, the new technology’s advantages include: no need to pin-point the water production location before water control jobs, little risk of damaging the reservoir during operations. The new technology has been applied in oilfields in western South China Sea, after implementation, the experimental well produced 30m3/D more oil at 20% less water cut, which provides a new option of water conformance technologies in offshore horizontal wells.

Physical modeling of failures of the automotive alternator

The relevance of the problem of automotive alternator diagnosis is associated with the imperfection of existing methods due to their significant complexity and lack of information. In order the accelerate the process of electrical failures diagnosis, the article considers their physical modelling method, the advantages of which are significant acceleration of the experiment, the possibility of modelling several failures, as well as the establishment of a clear boundary between the serviceable and non-serviceable states of the alternator. Adequately simulating the processes occurring in the alternator, physical modelling is implemented by means of serial or parallel connection to the alternator elements of adjustable active resistance. Experimental data show that the most informative and sensitive to the process of failures development is the temperature increase which can serve as the basis for on-board monitoring system aimed at determining the technical condition of an automotive alternator.

Numerical analysis of slide-head-toppling failure

In layered and blocky rock slopes, toppling failure is a common mode of instability that may occur in mining engineering. If this type of slope failure occurs as a consequence of another type of failure, it is referred to as the secondary toppling failure. “Slide-head-toppling” is a type of secondary toppling failures, where the upper part of the slope is toppled as a consequence of a semi-circular sliding failure at the toe of the slope. In this research work, the slide-head-toppling failure is examined through a series of numerical modeling. Phase 2, as a software written based on the finite element method, is used in this work. Different types of slide-head-toppling failures including blocky, block-flexural, and flexural are simulated. A good agreement can be observed when the results of the numerical modeling are compared with those for the pre-existing physical modeling and analytical method.

Construction Control Method and Application of Hydropower Project Based on Permanent and Temporary Monitoring

According to the permanent and temporary monitoring results, the warning boundary method and the mathematical physical model method are used for early warning and forecasting, and the construction measures are dynamically adjusted to form a construction control method based on safety monitoring technology. The application of the method which combines permanent monitoring with temporary monitoring on the front slope of the tail water outlet of the left bank, the upstream side wall of the 7#∼8# machine on the right bank, and the downstream abutment of the 9#∼10# unit section of Wudongde Hydropower Station, shows that it can fully grasp the stability of surrounding rock during construction period of slope and underground caverns. Through the early warning and forecasting, the mechanism of deformation is analyzed, the construction measures are adjusted in time, and the effect of the measures is evaluated, which plays an important role in ensuring the safety of the construction period.

SOFTWARE COMPLEX FOR SOLVING THE DIFFERENT TASKS OF PHYSICAL GAS DYNAMICS

This article is relevant due to the fact that The complexity of scientific problems solved by the methods of physical and mathematical modeling, the increasing requirements for the accuracy of their solution leads to an increase in the volume of data processed during the computational experiments. The aim of the work is to reduce the monetary and time costs for the work of scientific personnel which arise when using the weakly structured software that requires a large number of secondary activities not related to the activity on the performance of calculations, as well as providing the means of data exchange between the related research areas. This article discusses a computational algorithm and a set of software tools for modeling the fine structure of non-stationary multicomponent reactive gas flows and provides the structure of the complex, as well as the description of individual elements, and examples. A set of software tools for providing the numerical modeling of problems in the physical gas dynamics, including the graphic and information components supporting the resource-intensive stages of computational experiments is described. The complex of software tools consists of a graphical shell of control elements of the system; database of thermodynamic properties of substances and kinetic mechanisms, and the graphical interface for controlling it; module visualization of the results of solving computational problems; software components of the automated preparation of input data for the problem of modeling unsteady flows of the reacting gas. The developed set of programs can be used to solve the problems of the reacting gas dynamics, which are of practical importance, as well as the illustrator of training courses in the physical gas dynamics.

Energy conversion of urban wastes in China: Insights into potentials and disparities of regional energy and environmental benefits

With the rapid economic growth and urbanization, China is suffering from serious challenges on energy security and the problems regarding waste treatment and emissions mitigation. Converting urban wastes into energy has been recognized as a promising way to achieve circular economy. In this study, combustible waste, food waste, industrial organic wastewater, and breeding-farm manure are considered to be utilized for energy recovery through waste-to-energy (WtE) technologies. Accordingly, four WtE sectors for power generation are formed and introduced into the socioeconomic activities. A methodological framework is established by combining econometrics, physical input-output model and baseline method of clean development mechanism to evaluate the energy and environmental benefits in China’s 31 provincial regions during the period 2016–2025. The results reveal that the regions with more waste generation and power generation are Guangdong (11.82 billion kWh in 2025) and Jiangsu (11.43 billion kWh in 2025). Hebei has the largest accumulative mitigation potentials for the emissions of greenhouse gases, sulfur dioxide, nitrogen oxides, and soot and dust (577.57 Mt carbon dioxide equivalent, 1.79 Mt, 0.89 Mt and 16.22 Mt, respectively), followed by Guangdong and Zhejiang. Less developed regions in northwestern China such as Gansu, Qinghai and Ningxia have less energy recovery and mitigation potentials. Meanwhile, the changes in industrial structure contribute to more mitigations in the sectors of power and heat, coal mining, and oil and gas extraction. The quantification of the energy and environmental benefits and revelation of the features and disparities of waste utilization for energy recovery across regions can provide insights and managerial implications for better policy-making regarding regional waste management.

RATIONAL CONSTRUCTION AND TECHNOLOGICAL PARAMETERS OF WATER TREATMENT FACILITIES IN RURAL AREAS

In view of the development of cottage construction and enterprises of agricultural products processing, located mainly in rural areas, the development of high-efficient, reliable and easy-to-use treatment plants for the purification of domestic wastewater of low quality is very relevant.
 The objective of the research is to ensure the high quality purified water and minimize capital and operating costs.
 To solve this problem, the methods of physical and mathematical modeling were used, as well as numerical and analytical methods for determination and analysis of the parameters of treatment facilities operation.
 To use the latest advances in science and technology in the area of small-scale wastewater treatment facilities, which are typical for rural settlements and agro-industrial enterprises, in these conditions it is proposed to use bioreactors and contact clarifying filters.
 As the research has shown, water quality indicators of purified water change during the time of water filtration Tf and depend on the velocity of water filtration Vf and a specific cleanings capacity of the filter: at the beginning their values decrease as a result of accumulation of active sludge in the subfilter space, and then they begin to rise due to the increase of hydraulic resistance to water motion and removing this residual matter into filtered water.
 The article also presents the results of investigations on changes in the content of organic compounds in filtered water during the filtration cycle Тf by the biochemical oxygen consumption value (BOCV) depending on a water filtration rate Vf, m/h, and the amount of active sludge (specific dirt content of the filter G, kg/m2), as well as the changes in the content of suspended matter Сf.i. due to the same parameters.
 The recommendations on the effective operation of wastewater treatment facilities of the proposed design that which ensure their reliable and high-performance operation, were developed.

A web-based geovisual analytics platform for identifying potential contributors to culvert sedimentation.

Sediment accumulation at culverts involves large-scale and interlinked environmental processes that are difficult to address with experimental or physical modeling methods. This article presents an alternative data-driven investigation for shedding insights into these processes. Accordingly, a web-based geovisual analytics application, the IowaDOT platform, was developed, which allows users to explore the complex processes associated with the sediment deposition at culverts. The platform provides systematic procedures for (1) collecting and integrating analytical variables into a single dataset, (2) quantifying the degree of culvert sedimentation using time series of aerial images, (3) identifying drivers that contribute to culvert sedimentation processes from a variety of culvert structural and upstream landscape characteristics using a tree-based feature selection algorithm, and (4) facilitating the understanding of complex spatial and relational patterns of culvert sedimentation processes using multivariate geovisualizations supported by a self-organizing map (SOM). As the outcomes of this study, these patterns identify culvert sedimentation-prone regions in Iowa and quantify empirical relationships between the drivers and culvert sedimentation degrees. A simple evaluation of the platform was performed to assess the usefulness and user satisfaction of the tool by professional users, and positive feedbacks are received.

The study of the aerodynamic performance of a train using a physical simulation method

The paper analyzes the topicality of the research topic, identifies goals, objectives, subject and object of research. The analysis of known studies related to the study of the characteristics of the formation of the air resistance force during the movement of such vehicles as long-haul trains is given. Based on the analysis of the state of knowledge of the issue about the factors influencing the geometric parameters of road trains on aerodynamic drag, the relevance of the study is substantiated, their goal and objectives are formulated. As a result of the analysis of the methods and means of known studies, it was determined that the use of the method of physical modeling would be the most appropriate from the point of view of cost and complexity. An experimental setup has been created, which consists of a fan, an air flow rectifier and a scale model of an articulated train mounted on a special frame, as well as a device for measuring the air resistance force. Analytical studies have shown that the presence of gaps between the elements of the train (semi-trailer and trailer, tractor and trailer) significantly affects the amount of air resistance force, and, consequently, the energy consumption to overcome it. It is shown that the existing methods for calculating the magnitude of the force of air resistance do not take into account these features. The results of experimental studies have confirmed the need to eliminate these gaps. The measures to reduce the force of air resistance of road trains are proposed.

Studying the stiffness of thin-layered compositions with delaminations

As part of the construction, thin-layer compositions take loads, work in contact with various environments, and work under influence of physical fields. All this can lead to delamination of the compositions and changes in their mechanical properties. The method of physical modeling of compositions with defects in the form of delaminations is considered. The stiffness properties of thin-layer compositions with local delaminations are studied by experimental-theoretical method.

Geotechnical magnetic–similitude–gravity model testing method

Physical modelling under the gravitational field between 0 and ng plays a key role in both terrestrial- and aerospace-geotechnical engineering. A geotechnical magnetic–similitude–gravity model testing (GMMT) method is newly proposed to provide an alternative approach to the current physical modelling methods. The theoretical criteria for achieving a magnetic field to simulate the gravitational field are presented first, based on which an exact simulation of the stress field is achieved between the physical model and its corresponding prototype. A GMMT equipment is then designed and manufactured, and a related procedure for obtaining its control and input parameters is presented. Accordingly, the preparation of the model material is demonstrated utilising a kind of magnetically sensitive granular (MSG) media. The relationship between mechanical properties, magnetisation, magnetic–similitude–gravity and magnetic powder content of the MSG media are further investigated, and the influences of both magnetising field and magnetisation process are shown to be negligible in terms of mechanical behaviour. A series of physical modelling of the bearing capacity of granular media under low-gravity conditions is finally performed using the GMMT equipment. The results show good agreement with previous data obtained by the parabolic flight aircraft.

Time-variant characteristic under the piston wind on subway tunnel billboard

The study of the time-variant characteristic on billboards caused by the piston wind deals with the issue of the billboards falling out in the subway tunnel. A method of a full-scale physical model and the corresponding numerical model are established, and the dynamic meshing deformation to simulate the metro runs in the tunnel was used, where good agreement between the simulation result and the experimental result was achieved proving the model to be correct. On this basis, the flow field in the actual subway tunnel is simulated, and the wind pressure time-variant characteristic on the billboards is analyzed. The results demonstrate that the static pressure on the billboard surface goes through a series of changes: “uniform distribution – left and right gradient – up and down gradient – uniform distribution”. The billboard’s upper right corner of the driving direction is subjected to the largest pressure and hence most vulnerable to damage. This method can provide guidance to the installation and maintenance of billboards in practical engineering applications.

Development of a new physical modeling method to investigate the effect of porosity on the parameters of intact rock failure criteria

Porosity is a critical textural parameter in the complex nature of rock and while it has the highest impact on the strength of intact rock, in the case of oil and gas reservoir rocks, it defines the capacity and permeability of the reservoir. A constant value for triaxial strength factor (mi) of rock failure criterion has been given for each type of sedimentary rocks such as sandstone and the effect of porosity on the mi has not been well defined. Rock is not a homogenous material as with varying the porosity, the other inherent variables also control the strength and the mechanical behavior. Rock porosity varies in a wide range in sedimentary rocks such as sandstone. In this study, the effect of porosity on the parameters of failure criteria (mi) for rock-like materials made from cemented grains is investigated. For sample preparation, a mixture of cement-sand-water was compacted with variable water content to obtain specimens having a wide range of porosities using the same grain size of filler material. Two types of grains including sand and silica filler material were used for the experimental program. Sixteen sets of artificial specimens having porosities from 9.00% to 34.09% have been prepared for two filler materials of sand and silica, while other factors affecting the strength have been kept constant. The triaxial strength test results of these specimens show that the triaxial strength factor (mi) of Hoek et al. failure criterion, internal friction angle (ϕ), and cohesive strength (C) significantly decrease with increasing the porosity. The best-fit curves follow power function with high coefficients of regression.

The Study of Geomechanical Condition of Unstable Rocks in the Vicinity of Mine Working Junctions

The relevance of research of material strain nature based on physical models equivalent to rocks is substantiated. To identify the dependencies and mechanism of unstable rock strain in the vicinity of mine working junctions, an experimental technique has been developed and presented. The method of physical modeling using equivalent materials was applied in the research. Strength characteristics of the rock equivalent material were calculated using the formulas proposed by G.N. Kuznetsov. The equivalent material was prepared based on two components, sand and paraffin. The mix formulation was selected, and ultimate compressive strength of the equivalent material was determined. The experiment was performed for three options of the physical models: an intact rock mass, a rock mass with a single mine working, and a rock mass with mine working junctions. Testing of the models made of the equivalent material was performed through uniaxial vertical loading using a hydraulic press. Based on the model testing findings, the dynamics of fracture propagation and crushing of the enclosing equivalent material in the vicinity of an artificial cavity, simulating a mine working, has been demonstrated. Besides, the graphs of relative strain versus vertical loading for each stage of the stepwise loading of these three model options were produced. The findings of the strain-stress distribution modeling for the equivalent material around the cavities simulating mine working junctions were analyzed. The strain testing findings for the materials simulating rock behavior are expected to be used as the initial data for analysis of physical and numerical simulation, as well as for developing engineering documentation with regard to the selection of parameters for supporting mine working junctions.

Three-Dimensional Physical and Numerical Modelling of Fracturing and Deformation Behaviour of Mining-Induced Rock Slopes

Fracturing behaviour of jointed rock mass subjected to mining can significantly affect the stability of the rock structures and rock slopes. Ore mining within an open-pit final slope would lead to large-scale strata and surface movement of the rock slope. Rock mass structure, or more specifically, the strength, spacing and distribution of rock joints, are the controlling factors that govern the failure and deformation mechanisms of the final slope. Two-dimensional (2-D) physical modelling tests have been conducted in the literature, but in general, most of them have simplified the geological conditions and neglected some key features of rock mass structure in the field. In this study, new three-dimensional (3-D) physical modelling methods are introduced, with realistic modelling of mechanical behaviour of rock mass as well as identified properties of predominant rock joint sets. A case study of Yanqianshan iron mine is considered and the corresponding 1:200 model rock slope was created for studying the rock joint effects on the strata movement and the subsidence mechanism of the slope. The physical model test results are subsequently verified with 3-D discrete element numerical modelling. Due to the presence of the predominant joints, the observed well-shaped strata subsidence in Yanqianshan iron mine was successfully reproduced in the 3-D physical model. The failure mechanism of rock slopes differs from the trumpet-shaped subsidence observed in unconsolidated soil. Due to the formation of an arching mechanism within the rock mass, the strata deformation transferred gradually from the roof of the goaf to the slope surface.

Hydrodynamic performance of a newly-designed Antarctic krill trawl using numerical simulation and physical modeling methods

Antarctic krill (Euphausia superba) is one of the most abundant commercial species in the world and still has great potential for further development and utilization. It is, however, very important that the resource is utilized in a sustainable manner in terms of efficiency and selectivity, which can be enhanced through proper design of pelagic trawls that are used for harvesting the species. Pelagic trawls rely heavily on hydrodynamic forces acting on the netting to form desirable shapes. It is thus crucial to understand hydrodynamic forces acting on the trawl to predict its performance. A large Antarctic krill trawl with a net opening circumference of 200 m was designed for a fishing vessel (2855 kW) and analyzed by numerical simulation and physical model tests. A numerical model of Antarctic krill trawl was established based on the finite element method. The principle of minimum potential energy was employed to determine the equilibrium configuration and the tension distribution of the trawl in a uniform current. The Newton–Raphson method was applied to solve the equilibrium equation. A series of physical model tests were conducted in a flume tank to verify the result from numerical simulation. The results showed that the trawl with a net opening circumference of 200 m had superior hydrodynamic performance and could be well matched with fishing vessels of the class for the efficient production of Antarctic krill. This paper demonstrates the use of scientific methods for the design of large Antarctic krill trawls and the application of numerical simulation to study the hydrodynamic performance.

Retrieval of snow freeboard of Antarctic sea ice using waveform fitting of CryoSat-2 returns

Abstract. In this paper we develop a CryoSat-2 algorithm to retrieve the surface elevation of the air–snow interface over Antarctic sea ice. This algorithm utilizes a two-layer physical model that accounts for scattering from a snow layer atop sea ice as well as scattering from below the snow surface. The model produces waveforms that are fit to CryoSat-2 level 1B data through a bounded trust region least-squares fitting process. These fit waveforms are then used to track the air–snow interface and retrieve the surface elevation at each point along the CryoSat-2 ground track, from which the snow freeboard is computed. To validate this algorithm, we compare retrieved surface elevation measurements and snow surface radar return power levels with those from Operation IceBridge, which flew along a contemporaneous CryoSat-2 orbit in October 2011 and November 2012. Average elevation differences (standard deviations) along the flight lines (IceBridge Airborne Topographic Mapper, ATM – CryoSat-2) are found to be 0.016 cm (29.24 cm) in 2011 and 2.58 cm (26.65 cm) in 2012. The spatial distribution of monthly average pan-Antarctic snow freeboard found using this method is similar to what was observed from NASA's Ice, Cloud, and land Elevation Satellite (ICESat), where the difference (standard deviation) between October 2011–2017 CryoSat-2 mean snow freeboard and spring 2003–2007 mean freeboard from ICESat is 1.92 cm (9.23 cm). While our results suggest that this physical model and waveform fitting method can be used to retrieve snow freeboard from CryoSat-2, allowing for the potential to join laser and radar altimetry data records in the Antarctic, larger (∼30 cm) regional differences from ICESat and along-track differences from ATM do exist, suggesting the need for future improvements to the method. Snow–ice interface elevation retrieval is also explored as a potential to obtain snow depth measurements. However, it is found that this retrieval method often tracks a strong scattering layer within the snow layer instead of the actual snow–ice interface, leading to an overestimation of ice freeboard and an underestimation of snow depth in much of the Southern Ocean but with promising results in areas such as the East Antarctic sector.

Elastic-plastic Shock Processes Similarity

In the process of working out the design of the object, preliminary studies are carried out, including modeling (mathematical, physical or a combination of them) and comprehensive tests. In physical modeling, based on the methods of the theory of similarity and dimensions, the preparatory stages are implemented on the basis of an adequate mathematical model of the object or an in-depth description of its physical features. During stand testing the most complex problem is the problem of simulating an excitation in the form of intense single shock pulse. In stand shock testing in the contact is usually set an elastic-plastic, impact deformed element (crusher). The semi-empirical theory of impact is based on the assumption that only local elastic-plastic deformations could be taken into account. The study of the impact process is first illustrated using the method of physical modeling. In this two independent criteria of similarity of the shock processes are substantiated. Then, based on the analysis and numerical solution of the differential equation of impact, it is shown that the dimensionless complex arising from the theory of similarity and dimensions can be used to separately determine the main parameters of the shock process for given shock conditions – the duration of the load front and the maximum values of the contact force (overload) and local deformation. The experimental data obtained by means of a vertical pneumatic shock stand, having a small spread relative to the calculated results, are presented. The features of the process in the case of elastic-plastic impact of an elongated, rod type body are briefly considered. The criterion allowing to estimate quantitatively the relative role of wave processes in this variant of impact is offered which enables to validate conditions of considering the impacting body as a solid one.