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Academic literature on the topic 'Velocity and Density 3D models'
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Journal articles on the topic "Velocity and Density 3D models"
1
Guo, Peng, and George A. McMechan. "Sensitivity of 3D 3C synthetic seismograms to anisotropic attenuation and velocity in reservoir models." GEOPHYSICS 82, no. 2 (2017): T79—T95. http://dx.doi.org/10.1190/geo2016-0321.1.
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Anisotropic attenuation in fluid-saturated reservoirs with high fracture density may be diagnostic for reservoir characterization. Wave-induced mesoscale fluid flow is considered to be the major cause of intrinsic attenuation at exploration seismic frequencies. We perform tests of the sensitivity, of anisotropic attenuation and velocity, to reservoir properties in fractured HTI media based on the mesoscale fluid flow attenuation mechanism. The viscoelastic T-matrix, a unified effective medium theory of global and local fluid flow mechanisms, is used to compute frequency-dependent anisotropic attenuation and velocity for ranges of reservoir properties, including fracture density, orientation, fracture aspect ratio, fluid type, and permeability. The 3D 3C staggered-grid finite-difference anisotropic viscoelastic modeling with a Crank-Nicolson scheme is used to generate seismograms using the frequency-dependent velocity and attenuation computed by the viscoelastic T-matrix. A standard linear solid model relates the stress and strain relaxation times to the frequency-dependent attenuation, in the relaxation mechanism equation. The seismic signatures resulting from changing viscoelastic reservoir properties are easily visible. Velocity becomes more sensitive to the fracture aspect ratio when considering fluid flow compared with when the fluid is isolated. Anisotropy of attenuation affects 3C viscoelastic seismic data more strongly than velocity anisotropy does. Analysis of the influence of reservoir properties, on seismic properties in mesoscale fluid-saturated fractured reservoirs with high fracture density, suggests that anisotropic attenuation is a potential tool for reservoir characterization.
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Huang, Long, Robert R. Stewart, Nikolay Dyaur, and Jose Baez-Franceschi. "3D-printed rock models: Elastic properties and the effects of penny-shaped inclusions with fluid substitution." GEOPHYSICS 81, no. 6 (2016): D669—D677. http://dx.doi.org/10.1190/geo2015-0655.1.
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3D printing techniques (additive manufacturing) using different materials and structures provide opportunities to understand porous or fractured materials and fluid effects on their elastic properties. We used a 3D printer (Stratasys Dimension SST 768) to print one “solid” cube model and another with penny-shaped inclusions. The 3D printing process builds materials, layer by layer, producing a slight “bedding” plane, somewhat similar to a sedimentary process. We used ultrasonic transducers (500 kHz) to measure the P- and S-wave velocities. The input printing material was thermoplastic with a density of [Formula: see text], P-wave velocity of [Formula: see text], and S-wave velocity of [Formula: see text]. The solid cube had a porosity of approximately 6% and a density of [Formula: see text]. Its P-wave velocity was [Formula: see text] in the bedding direction and [Formula: see text] normal to bedding. We observed S-wave splitting with fast and slow velocities of 879 and [Formula: see text], respectively. Quality factors for P- and S-waves were estimated using the spectral-ratio method with [Formula: see text] ranging from 15 to 17 and [Formula: see text] from 24 to 27. By introducing penny-shaped inclusions along the bedding direction in a 3D printed cube, we created a more porous volume with density of [Formula: see text] and porosity of 24%. The inclusions significantly decreased the P-wave velocity to 1706 and [Formula: see text] parallel and normal to the bedding plane. The fast and slow S-wave velocities also decreased to 812 and [Formula: see text]. A fluid substitution experiment, performed with water, increased (20%–46%) P-wave velocities and decreased (9%–10%) S-wave velocities. Theoretical predictions using Schoenberg’s linear-slip theory and Hudson’s penny-shaped theory were calculated, and we found that both theories matched the measurements closely (within 5%). The 3D printed material has interesting and definable properties and is an exciting new material for understanding wave propagation, rock properties, and fluid effects.
3
Ishikawa, Mayra, Wendy Gonzalez, Orides Golyjeswski, et al. "Effects of dimensionality on the performance of hydrodynamic models for stratified lakes and reservoirs." Geoscientific Model Development 15, no. 5 (2022): 2197–220. http://dx.doi.org/10.5194/gmd-15-2197-2022.
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Abstract. Numerical models are an important tool for simulating temperature, hydrodynamics, and water quality in lakes and reservoirs. Existing models differ in dimensionality by considering spatial variations of simulated parameters (e.g., flow velocity and water temperature) in one (1D), two (2D) or three (3D) spatial dimensions. The different approaches are based on different levels of simplification in the description of hydrodynamic processes and result in different demands on computational power. The aim of this study is to compare three models with different dimensionalities and to analyze differences between model results in relation to model simplifications. We analyze simulations of thermal stratification, flow velocity and substance transport by density currents in a medium-sized drinking-water reservoir in the subtropical zone, using three widely used open-source models: GLM (1D), CE-QUAL-W2 (2D) and Delft3D (3D). The models were operated with identical initial and boundary conditions over a 1-year period. Their performance was assessed by comparing model results with measurements of temperature, flow velocity and turbulence. Our results show that all models were capable of simulating the seasonal changes in water temperature and stratification. Flow velocities, only available for the 2D and 3D approaches, were more challenging to reproduce, but 3D simulations showed closer agreement with observations. With increasing dimensionality, the quality of the simulations also increased in terms of error, correlation and variance. None of the models provided good agreement with observations in terms of mixed layer depth, which also affects the spreading of inflowing water as density currents and the results of water quality models that build on outputs of the hydrodynamic models.
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Kurapati, Sushma, Jayaram N. Chengalur, Peter Kamphuis, and Simon Pustilnik. "Mass models of gas-rich void dwarf galaxies." Monthly Notices of the Royal Astronomical Society 491, no. 4 (2019): 4993–5014. http://dx.doi.org/10.1093/mnras/stz3334.
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ABSTRACT We construct mass models of eight gas rich dwarf galaxies that lie in the Lynx–Cancer void. From NFW fits to the dark matter halo profile, we find that the concentration parameters of haloes of void dwarf galaxies are similar to those of dwarf galaxies in normal density regions. We also measure the slope of the central dark matter density profiles, obtained by converting the rotation curves derived using 3D (fat) and 2D (ROTCUR) tilted ring fitting routines, into mass densities. We find that the average slope (α = −1.39 ± 0.19), obtained from 3D fitting is consistent with that expected from an NFW profile. On the other hand, the average slope measured using the 2D approach is closer to what would be expected for an isothermal profile. This suggests that systematic effects in velocity field analysis have a significant effect on the slope of the central dark matter density profiles. Given the modest number of galaxies we use for our analysis, it is important to check these results using a larger sample.
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KARTOON, D., D. ORON, L. ARAZI, and D. SHVARTS. "Three-dimensional multimode Rayleigh–Taylor and Richtmyer–Meshkov instabilities at all density ratios." Laser and Particle Beams 21, no. 3 (2003): 327–34. http://dx.doi.org/10.1017/s0263034603213069.
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The three-dimensional (3D) turbulent mixing zone (TMZ) evolution under Rayleigh–Taylor and Richtmyer–Meshkov conditions was studied using two approaches. First, an extensive numerical study was made, investigating the growth of a random 3D perturbation in a wide range of density ratios. Following that, a new 3D statistical model was developed, similar to the previously developed two-dimensional (2D) statistical model, assuming binary interactions between bubbles that are growing at a 3D asymptotic velocity. Confirmation of the theoretical model was gained by detailed comparison of the bubble size distribution to the numerical simulations, enabled by a new analysis scheme that was applied to the 3D simulations. In addition, the results for the growth rate of the 3D bubble front obtained from the theoretical model show very good agreement with both the experimental and the 3D simulation results. A simple 3D drag–buoyancy model is also presented and compared with the results of the simulations and the experiments with good agreement. Its extension to the spike-front evolution, made by assuming the spikes' motion is governed by the single-mode evolution determined by the dominant bubbles, is in good agreement with the experiments and the 3D simulations. The good agreement between the 3D theoretical models, the 3D numerical simulations, and the experimental results, together with the clear differences between the 2D and the 3D results, suggest that the discrepancies between the experiments and the previously developed models are due to geometrical effects.
6
Sharov, N. V., L. I. Bakunovich, B. Z. Belashev, and M. Y. Nilov. "Velocity structure and density inhomogeneities of the White Sea crust." Arctic: Ecology and Economy, no. 4(40) (December 2020): 43–53. http://dx.doi.org/10.25283/2223-4594-2020-4-43-53.
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The study area is the White Sea basin and adjacent territories. The relevance of the work carried out here is determined by active geodynamics, kimberlite magmatism, and prospects for the hydrocarbon search. The authors set the goal to model the velocity structure of the region’s crust using data from instrumental observations and the Integro software package. A comprehensive interpretation of gravimetric, magnetometric, seismic, petrophysical and geological data has been carried out. With the help of 2D models based on the DSZ profiles and digital maps of geophysical fields, refined density structures of local sections of the earth’s crust have been specified. The developed 3D density model gives a general picture of the deep structure of the region’s crust. Within its framework, the spatial positions of the layers of the velocity reference model are determined and their connections with density inhomogeneities and geophysical anomalies are established.
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Sukhinov, A., A. Chistyakov, S. Protsenko, and E. Protsenko. "Study of 3D discrete hydrodynamics models using cell filling." E3S Web of Conferences 224 (2020): 02016. http://dx.doi.org/10.1051/e3sconf/202022402016.
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Modern methods and tools for coastal hydrodynamics modeling indicate the necessity of constructing discrete analogs of models for ones the properties: balance and conservation laws (for mass, flows, impulse), stability, convergence and etc. have been fulfilled. The paper considers a continuous three-dimensional mathematical model of the hydrodynamics of water basins and its discretization. The pressure correction method at variable water medium density was used to solve the problem of hydrodynamics. The considered discrete mathematical models of hydrodynamics take into account the filling of control cells on rectangular grids. This increased the accuracy of the solution in the case of complex geometry by improving the boundary approximation. From the obtained estimates of the components of the velocity vector, it follows that there are no two or more stationary regimes in which all forces are balanced, and the solution to the discrete problem exists and is unique and tends to the solution of the continuous problem upon reaching the stationary regime. Also the balance of the flows for the discrete model has been proved as well as absence of non-conservative dissipative terms.
8
Qiu, Ruofan, Rongqian Chen, Chenxiang Zhu, and Yancheng You. "A Hermite-based lattice Boltzmann model with artificial viscosity for compressible viscous flows." International Journal of Modern Physics B 32, no. 13 (2018): 1850157. http://dx.doi.org/10.1142/s0217979218501576.
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A lattice Boltzmann model on Hermite basis for compressible viscous flows is presented in this paper. The model is developed in the framework of double-distribution-function approach, which has adjustable specific-heat ratio and Prandtl number. It contains a density distribution function for the flow field and a total energy distribution function for the temperature field. The equilibrium distribution function is determined by Hermite expansion, and the D3Q27 and D3Q39 three-dimensional (3D) discrete velocity models are used, in which the discrete velocity model can be replaced easily. Moreover, an artificial viscosity is introduced to enhance the model for capturing shock waves. The model is tested through several cases of compressible flows, including 3D supersonic viscous flows with boundary layer. The effect of artificial viscosity is estimated. Besides, D3Q27 and D3Q39 models are further compared in the present platform.
9
Moens, Nicolas, and Levin Hennicker. "The first 3D models of evolved hot star outflows." Proceedings of the International Astronomical Union 16, S366 (2020): 15–20. http://dx.doi.org/10.1017/s1743921322000230.
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AbstractThe mechanisms driving mass loss from massive stars in late stages of their evolution is still very much unknown. Stellar evolution models indicate that the last stage before going supernova for many massive stars is the Wolf-Rayet (WR) phase, characterized by a strong, optically thick stellar wind. Stellar models show that these stars exceed the Eddington limit already in deep sub-surface layers around the so-called ‘iron-opacity’ bump, and so should launch a supersonic outflow from there. However, if the outward force does not suffice to accelerate the gas above the local escape speed, the initiated flow will stagnate and start raining down upon the stellar core. In previous, spherically symmetric, WR wind models, this has been circumvented by artificially increasing either clumping or the line force. Here, we present pioneering 3D time-dependent radiation-hydrodynamic simulations of WR winds. In these models, computed without any ad-hoc force enhancement, the stagnated flow leads to co-existing regions of up- and down-flows, which dynamically interact with each other to form a multi-dimensional and complex outflow. These density structures, and the resulting highly non-monotonic velocity field, can have important consequences for mass-loss rates and the interpretation of observed Wolf-Rayet spectra.
10
Zhang, Jian, Chi‐Yuen Wang, Yaolin Shi, et al. "Three‐dimensional crustal structure in central Taiwan from gravity inversion with a parallel genetic algorithm." GEOPHYSICS 69, no. 4 (2004): 917–24. http://dx.doi.org/10.1190/1.1778235.
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The genetic algorithm method is combined with the finite‐element method for the first time as an alternative method to invert gravity anomaly data for reconstructing the 3D density structure in the subsurface. The method provides a global search in the model space for all acceptable models. The computational efficiency is significantly improved by storing the coefficient matrix and using it in all forward calculations, then by dividing the region of interest into many subregions and applying parallel processing to the subregions. Central Taiwan, a geologically complex region, is used as an example to demonstrate the utility of the method. A crustal block 120 × 150 km2 in area and 34 km in thickness is represented by a finite‐element model of 76 500 cubic elements, each 2 × 2 × 2 km3 in size. An initial density model is reconstructed from the regional 3D tomographic seismic velocity using an empirical relation between velocity and density. The difference between the calculated and the observed gravity anomaly (i.e., the residual anomaly) shows an elongated minimum of large magnitude that extends along the axis of the Taiwan mountain belt. Among the interpretive models tested, the best model shows a crustal root extending to depths of 50 to 60 km beneath the axis of the Western Central and Eastern Central Ranges with a density contrast of 400 or 500 kg/m3 across the Moho. Both predictions appear to be supported by independent seismological and laboratory evidence.