scholarly journals Metallic and glass spherules in the loose deposits of the Put river head (Middle Urals)

LITOSFERA ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 273-282
Author(s):  
S. G. Sustavov ◽  
V. A. Dushin ◽  
I. A. Vlasov ◽  
A. K. Trutnev ◽  
E. A. Zhuklin ◽  
...  
Keyword(s):  
Middle Urals ◽  
Two Phase ◽  
Mesh Structure ◽  
Fine Mesh ◽  
Modern Soil ◽  
Composition And Structure ◽  
Loose Deposits ◽  
Tectonic Zones ◽  
Neogene Sediments ◽  
Iron Chromium

Research subject. The article examines exotic mineral formations - spherules (balls) of various composition and structure, found in the Neogene sediments of the interfluve of the Put-Bisert rivers within the eastern wing of the Yurizan-Sylva de-pression.Materials and methods. The work was carried out using the authors' research results, the available data on similar formations both from the modern soil-vegetation layer, including peat and technogenic formations, and from more ancient Phanerozoic sedimentary, magmatic and ore complexes. The article uses the results of studies obtained by a scanning electron microscope “EVO MA 15” from ZEISS with an energy-dispersive attachment EDS “X-MAX 80” at the JSC “Mekhanobr” analytical laboratory.Results. A detailed study of the surface morphology, dimensions, chemical and mineral composition of three types of spherules - magnetite, iron-chromium composition and barium and titanium oxide, similar to the stoichiometric formula of sanbornite - was carried out. The surface of the balls of the second type is heterogeneous in structure and contains growths, some of which have the form of a flat, flattened, square, skeletal crystal of a sectorial structure. The inner surface of the crystal has a fine-mesh structure. The cells have a complex, elongated structure. At the periphery of the crystal, the cells transform into hollow channels, indicating growth from the gas phase. In composition, the sectoral crystal corresponds to a solid solution between magnesio-chromite and herzenite with an admixture of nickel, calcium and silicon. The internal microstructure of iron-chromium spherules has a myrmekite, two-phase structure.Conclusions. The obtained data indicate that such heterogeneous formations can be formed only in specific deep fluid-saturated high-temperature magmatic systems and delivered to the surface by hydrothermal fluids along weakened tectonic zones. The detection of these formations in the overlying sediments of the western wing of the Artinskaya anticline may indicate the proximity of large fluid-supplying deep structures that control the Bukharovskoye gas show.

scholarly journals Grid convergence study of a cyclone separator using different mesh structures

2017 ◽  
Vol 23 (3) ◽  
pp. 311-320 ◽  
Author(s):  
R.A.F. Oliveira ◽  
G.H. Justi ◽  
G.C. Lopes
Keyword(s):  
Pressure Drop ◽  
Collection Efficiency ◽  
Fluid Dynamic ◽  
Two Phase ◽  
Mesh Structure ◽  
Pressure Drops ◽  
Regular Elements ◽  
Grid Convergence ◽  
Grid Convergence Index ◽  
Mesh Structures

In a cyclone design, pressure drop and collection efficiency are two important performance parameters to estimate its implementation viability. The optimum design provides higher efficiencies and lower pressure drops. In this paper, a grid independence study was performed to determine the most appropriate mesh to simulate the two-phase flow in a Stairmand cyclone. Computational fluid dynamic (CFD) tools were used to simulate the flow in an Eulerian-Lagrangian approach. Two different mesh structure, one with wall-refinement and the other with regular elements, and several mesh sizes were tested. The grid convergence index (GCI) method was applied to evaluate the result independence. The CFD model results were compared with empirical correlations from bibliography, showing good agreement. The wall-refined mesh with 287 thousand elements obtained errors of 9.8% for collection efficiency and 14.2% for pressure drop, while the same mesh, with regular elements, obtained errors of 8.7% for collection efficiency and 0.01% for pressure drop.

Optimization of Strut Placement in Flow Diverter Stents for Four Different Aneurysm Configurations

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Hitomi Anzai ◽  
Jean-Luc Falcone ◽  
Bastien Chopard ◽  
Toshiyuki Hayase ◽  
Makoto Ohta
Keyword(s):  
Arterial Occlusion ◽  
Flow Simulation ◽  
Flow Diverter ◽  
Optimal Placement ◽  
Parent Artery ◽  
High Porosity ◽  
Mesh Structure ◽  
Flow Reduction ◽  
Fine Mesh ◽  
Flow Diverter Stent

A modern technique for the treatment of cerebral aneurysms involves insertion of a flow diverter stent. Flow stagnation, produced by the fine mesh structure of the diverter, is thought to promote blood clotting in an aneurysm. However, apart from its effect on flow reduction, the insertion of the metal device poses the risk of occlusion of a parent artery. One strategy for avoiding the risk of arterial occlusion is the use of a device with a higher porosity. To aid the development of optimal stents in the view point of flow reduction maintaining a high porosity, we used lattice Boltzmann flow simulations and simulated annealing optimization to investigate the optimal placement of stent struts. We constructed four idealized aneurysm geometries that resulted in four different inflow characteristics and employed a stent model with 36 unconnected struts corresponding to the porosity of 80%. Assuming intracranial flow, steady flow simulation with Reynolds number of 200 was applied for each aneurysm. Optimization of strut position was performed to minimize the average velocity in an aneurysm while maintaining the porosity. As the results of optimization, we obtained nonuniformed structure as optimized stent for each aneurysm geometry. And all optimized stents were characterized by denser struts in the inflow area. The variety of inflow patterns that resulted from differing aneurysm geometries led to unique strut placements for each aneurysm type.

scholarly journals ANALYSIS OF GEOMETRIC CHARACTERISTICS OF TWO-PHASE POLYMER-SOLVENT SYSTEMS DURING THE SEPARATION OF SOLUTIONS ACCORDING TO THE INTENSITY OF THE IMAGE OF MICROGRAPHS

2019 ◽  
Vol 16 (32) ◽  
pp. 551-559
Author(s):  
Nikolay A. BULYCHEV ◽  
Valeriy V. BODRYSHEV ◽  
Lev N. RABINSKIY
Keyword(s):  
Image Processing ◽  
Digital Image Processing ◽  
Digital Image ◽  
Droplet Surface ◽  
Droplet Growth ◽  
Two Phase ◽  
Image Intensity ◽  
Composition And Structure ◽  
Physical And Chemical ◽  
Instrumental Methods

This paper discusses the study of the shapes and sizes of polymer droplets formed during the phase separation of their solutions with increasing temperature, as well as the parameters of the transitional layers of polymer condensing on the droplet surface formed during this process. For the study, a copolymer of polyethylene oxide and polypropylene oxide was chosen, whose behavior in aqueous solutions and the change in hydrophilic-hydrophobic balance depends on temperature. It has been established that the application of the method of digital image processing allows the introduction of the quantitative criterion – image intensity of a photo. For a more detailed study of the behavior of polymer molecules at the phase boundary, depending on the temperature, the studies of the temperature-dependent behavior of a number of polymers of different composition and structure have been carried out. The use of the digital image processing method for polymer droplets makes it possible to determine the parameters of droplets and their transition layers, to determine the dynamics of nucleation and droplet growth and density changes in the transition layer by the image intensity parameter. The paper has found out that embryos of pluronic are unevenly distributed by volume of solution with the presence of zones with a maximum number of molecules and a zone with a minimum of assembly of molecules. The practical value of the work is in the fact that the results of the study can be used to assess the dynamics of the separation of polymer solutions without involving the time-consuming and expensive instrumental methods of physical and chemical analysis.

Numerical Investigation of a Steam Nozzle with Focus on Non-Equilibrium Condensation and Unsteady Flow Behavior

2019 ◽  
Vol 15 (1) ◽  
pp. 25-36
Author(s):  
Hari Bahadur Dura
Keyword(s):  
Correction Factor ◽  
Nucleation Rate ◽  
Flow Behavior ◽  
Droplet Diameter ◽  
Two Phase ◽  
Fine Mesh ◽  
Small Flow ◽  
Total Temperature ◽  
Steady Simulation ◽  
Non Equilibrium

Present work analyses the condensation of superheated water vapor in supersonic Barschdorff nozzle. The influence of pneumatic mounts in 3D laval nozzle is analyzed using steady and unsteady two phase non-equilibrium condensation steam flow model in Ansys CFX16. Mesh independency studies in 2D model showed that at a lower inlet total temperature and very fine mesh (e.g. 100.2°C and 77k mesh elements) there is problem with the convergence using steady simulation. This is possibly due to the ability of very fine mesh to capture the small flow unsteadiness. The variation in location of Wilson’s point, Wilson’s pressure and maximum sub-cooling rate at the centerline of the nozzle is below 1.5%. The 2D CFD nucleation rate is 50% stronger and droplet diameter is 18% higher compared to the 3D CFD results. The deviation in nucleation rate and droplet diameter at nozzle outlet is the result of dissipation due to wing structure in the 3D model. Nucleation zone predicted by Ansys CFX16 is far upstream the experimental one. Different correction factors in modified nucleation model were used to fit the computed pressure distribution with the experimental one. The correction factor is dependent on boundary conditions and nozzle profile. It is thus concluded that the significance of such correction factor is not unique.  

Development and Verification of Unstructured Adaptive Mesh Technique With Edge Compatibility

2009 ◽  
Author(s):  
Kei Ito ◽  
Tomoaki Kunugi ◽  
Hiroyuki Ohshima
Keyword(s):  
High Precision ◽  
Flow Simulation ◽  
Adaptive Mesh ◽  
Two Dimensional ◽  
Initial State ◽  
Two Phase ◽  
Fine Mesh ◽  
Distorted Mesh ◽  
Cfd Method ◽  
Mesh Technique

In a design study of the large-sized sodium-cooled fast reactors in Japan (JSFR), one key issue to establish an economically superior design is suppression of a gas entrainment (GE) phenomenon at a free surface in the reactor vessel. However, the GE phenomenon is highly non-linear and too difficult to be evaluated theoretically. Therefore, we are developing a high-precision CFD method to evaluate the GE phenomenon accurately. The CFD method is formulated on an unstructured mesh to establish an accurate modeling for a complicated shape of the JSFR system. As a two-phase flow simulation method, a high-precision volume-of-fluid algorithm is employed in the CFD method. In addition, physically appropriate formulations at gas-liquid interfaces are introduced into the CFD method. The developed CFD method is already applied to the simulation of a GE phenomenon in a basic GE experiment and the simulation results show good agreement with experimental results. Therefore, it is confirmed that the proposed CFD method can reproduce a GE phenomenon. However, for the simulation of the GE phenomenon in the JSFR, we still have one problem on a mesh subdivision. Though a fine mesh subdivision has to be applied to the regions where the GE occurs, it is difficult to preliminarily know the regions because the GE occurrence is strongly affected by a local instant flow pattern, i.e. a vortex generation. Therefore, an adaptive mesh technique is necessary to apply a fine mesh subdivision automatically to only the local GE occurrence regions in the large-sized JSFR. In this study, as one part of an adaptive mesh development, a two-dimensional unstructured adaptive mesh technique is developed and verified. In the proposed two-dimensional adaptive mesh technique, each cell is isotropically subdivided to reduce distortions of the mesh. In addition, a connection cell is formed to eliminate the edge incompatibility between a refined and a non-refined cells. A connection cell has several subdivision patterns and one of them is selected to be compatible with adjacent cells on every cell edge. Finally, the present unstructured adaptive mesh technique is verified by solving well-known driven cavity problem. As the result, the present unstructured adaptive mesh technique succeeds in providing a high-precision solution, although we employ a poor-quality distorted mesh at the initial state. In addition, the simulation error on the unstructured adaptive mesh at the steady state is much less than the error on the structured mesh consisting of a larger number of cells.

Magnetic Clusters in Natural Ferro-Chromian Spinels

2015 ◽  
Vol 233-234 ◽  
pp. 587-590
Author(s):  
Tatyana Sherendo ◽  
Valentin Mitrofanov ◽  
Aleksey Vdovin ◽  
Petr Martyshko ◽  
Aleksey Alexeev ◽  
...  
Keyword(s):  
Magnetic Force ◽  
Chrome Spinel ◽  
Middle Urals ◽  
Magnetic Clusters ◽  
Magnetic Dipoles ◽  
Force Microscopy ◽  
Geological Processes ◽  
Or Groups ◽  
Natural Iron ◽  
Iron Chromium

The results of investigations of natural iron-chromium spinels of variable composition Fe2+(Cr2-xFex3+)O4 of the chromite-bearing Klyuchevskoi massif (Middle Urals), which are the main carriers of the magnetization of rocks are presented. Substantial changes in the composition and in magnetic structure of accessory chrome-spinels scattered in the host rock are established, unlike the almost unaltered ore-forming chrome-spinels, under the influence of secondary geological processes. To establish the connection between the chrome-spinel changes at the microlevel and features of the geomagnetic field anomalies created by this carrier of magnetization of rocks, it is carried out a complex of investigations of Fe-Cr-spinels (thermomagnetic analysis over the temperature range (4÷1000) K; magnetic resonance (MR) spectroscopy and magnetic force microscopy (MFM) in addition to magnetomineralogical studies). As a result, in the relict areas of grains of the accessory chrome-spinels were first discovered the magnetic clusters (superparamagnetic phases) in the form of single or groups of 2 – 3 magnetic dipoles of tens nanometers in size, or in the form of chain-like structures of magnetic dipoles/single domains.

Thermoelastic Stress Analysis of Nitinol Self-Expanding Stents

2006 ◽  
Vol 3-4 ◽  
pp. 47-52 ◽  
Author(s):  
James Eaton-Evans ◽  
Janice M. Dulieu-Barton ◽  
Edward G. Little ◽  
Ian A. Brown
Keyword(s):  
Stress Analysis ◽  
Medical Devices ◽  
Thermoelastic Stress ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Thermoelastic Stress Analysis ◽  
Mesh Structure ◽  
Fine Mesh ◽  
Nitinol Stents ◽  
Thermoelastic Response

Self-expanding stents are small medical devices used to treat vascular disease and are typically fabricated from a super-elastic, shape memory alloy known as Nitinol and have a fine mesh structure. This paper describes preliminary work on the application of Thermoelastic Stress Analysis (TSA) to Nitinol stents. Uniaxial tensile tests were conducted on thin tubes of Nitinol to characterise the material mechanical properties. TSA calibration exercises were conducted, which showed that Nitinol exhibits a non-uniform thermoelastic response through its elastic region that corresponded to the superelastic behaviour. Initial TSA demonstrated that a viable thermoelastic signal could be obtained from the stents. In high resolution tests the effect of motion and noise were considerable but it was still possible to obtain a readable thermoelastic signal.

Towards a Detailed Liquid Fuel Injection Model for Gas Turbine Combustor CFD

2020 ◽  
Author(s):  
L. Wang ◽  
H. Ozogul ◽  
T. Kaushik ◽  
A. Bhat ◽  
S. Rida
Keyword(s):  
Boundary Condition ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Initial Conditions ◽  
Model Performance ◽  
Fuel Spray ◽  
Two Phase ◽  
Lagrangian Simulation ◽  
Fine Mesh ◽  
Injection Model

Abstract Fuel injection modeling plays an important role in Computational Fluid Dynamics (CFD) based combustor design and performance analysis. The specification of initial fuel spray size, velocity, and location strongly affects the subsequent fuel air mixing and combustion processes. Current common practice of introducing fuel spray in combustor CFD relies on either experimental correlations built from spray data measured at locations further away from injector exit or simplified theoretical models that have limited applications. This often leads to large uncertainties in spray initial conditions and inconsistencies in combustor model performance. Although much progress has been made in multiphase simulation of primary atomization, involving a two-phase flow solver in combustor CFD to resolve liquid fuel injection processes is still not feasible in the foreseeable future. Standalone fuel injection simulations, however, can provide valuable information on initial spray distributions required for accurate fuel injection modeling in combustor CFD. In this paper the approach of using a standalone or separate detailed fuel injection simulation to provide initial spray boundary condition for combustor CFD is demonstrated in a Liquid Jet In Cross Flow (LJICF) configuration. The primary atomization (PA) of the LJICF is simulated using a Volume of Fluid (VOF) solver on a fine mesh, and the blobs and ligaments from the PA simulation are collected and transferred to another separate simulation of spray using a Lagrangian particle tracking solver on a coarser mesh. The results from the Lagrangian simulation are compared with experimental data as well as the results from a conventional fuel injection model. The differences from the comparisons are discussed to reveal the challenges and new modeling needs associated with this detailed fuel injection model. These include the effect of mesh resolution on the spray boundary condition, the need for blockage modeling, and the need for ligament breakup modeling.

3DP process for fine mesh structure printing

2008 ◽  
Vol 187 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Kathy Lu ◽  
William T. Reynolds
Keyword(s):  
Mesh Structure ◽  
Fine Mesh

scholarly journals RELAP5 Analysis of OECD/NEA ROSA Project Experiment Simulating a PWR Loss-of-Feedwater Transient with High-Power Natural Circulation

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Takeshi Takeda ◽  
Hideaki Asaka ◽  
Hideo Nakamura
Keyword(s):  
Flow Rate ◽  
High Power ◽  
Natural Circulation ◽  
Liquid Level ◽  
Injection System ◽  
Relief Valve ◽  
Two Phase ◽  
Fine Mesh ◽  
Post Test ◽  
Long Time

A ROSA/LSTF experiment was conducted for OECD/NEA ROSA Project simulating a PWR loss-of-feedwater (LOFW) transient with specific assumptions of failure of scram that may cause natural circulation with high core power and total failure of high pressure injection system. Auxiliary feedwater (AFW) was provided to well observe the long-term high-power natural circulation. The core power curve was obtained from a RELAP5 code analysis of PWR LOFW transient without scram. The primary and steam generator (SG) secondary-side pressures were maintained, respectively, at around 16 and 8 MPa by cycle opening of pressurizer (PZR) power-operated relief valve and SG relief valves for a long time. Large-amplitude level oscillation occurred in SG U-tubes for a long time in a form of slow fill and dump while the two-phase natural circulation flow rate gradually decreased with some oscillation. RELAP5 post-test analyses were performed to well understand the observed phenomena by employing a fine-mesh multiple parallel flow channel representation of SG U-tubes with a Wallis counter-current flow limiting correlation at the inlet of U-tubes. The code, however, has remaining problems in proper predictions of the oscillative primary loop flow rate and SG U-tube liquid level as well as PZR liquid level.

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