SEARCH · Search NASA

Results for “3D Simulation”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35

All sources NASA NTRS DOE OSTI

DOE OSTI2022

Simulation and analysis of the 3D double shock-induced recompression of spall using a hybrid PAGOSA with FLIP+MPM

In this work, an innovative hybrid algorithm PAGOSA with FLIP + MPM is first presented by coupling PAGOSA with the particle FLIP + MPM, and applied to systematically exploring the 3D recompression of spall induced by double-shock waves in ductile materials as the few existing studies are currently limited to the pure longitudinal recompression of spall, and ignore the 3D effects. This algorithm solves the difficulties the grid-based methods encounter when applied to capturing the fracture in material. We first validate the capabilities of PAGOSA with FLIP + MPM to predict different fracture/fragmentation cases by solving two benchmark problems and comparing with the analytical solutions or the experiment results. The convergences and the infinity-norm errors are also investigated. Subsequently, the 3D effects are demonstrated by simulating the spallation in material using PAGOSA with FLIP + MPM and comparing with those in the longitudinal cases. Additionally, some factors that affect the spallation with 3D effects are also discussed. Finally, the recompressions of spall in material with/without 3D effects are systematically simulated and analyzed. The recompression of spall driven by a high explosive is also simulated to show the ability of PAGOSA with FLIP + MPM to handle this kind of problem. The conditions that can lead to a recompression of spall are explored. Also, numerical results show that PAGOSA with FLIP + MPM can accurately predict different fracture cases, that the 3D effects play an important role in fracture/fragmentation, and the recompression of spall is very sensitive to the occurrence conditions, shows great differences when considering 3D effects in real applications. Moreover, the present hybrid method can be easily extended to other grid-based techniques employed for fracture in materials.

3D effects↗

DOE OSTI2025

Three-dimensional reconstruction of inertial confinement fusion hot-spot plasma from x-ray and nuclear diagnostics on OMEGA

Multidimensional effects degrade the neutron yield and the compressed areal density of laser-direct-drive inertial confinement fusion implosions of layered deuterium–tritium cryogenic targets on the OMEGA Laser System with respect to 1D radiation-hydrodynamic simulation predictions. A comprehensive physics-informed 3D reconstruction effort is under way to infer hot-spot and shell conditions at stagnation from four x-ray and seven neutron detectors distributed around the OMEGA target chamber. Neutron diagnostics, providing measurements of the neutron yield, hot-spot flow velocity, and apparent ion-temperature distribution, are used to infer the mode-1 perturbation at stagnation. The x-ray imagers record the shape of the hot-spot plasma to diagnose mode-1 and mode-2 perturbations. A deep-learning convolutional neural network trained on an extensive set of 3D radiation-hydrodynamic simulations is used to interpret the x-ray and nuclear measurements to infer the 3D profiles of the hot-spot plasma conditions and the amount of laser energy coupled to the hot-spot plasma. A 3D simulation database shows that larger mode-1 asymmetries are correlated with higher hot-spot flow velocities and reduced laser-energy coupling and neutron yield. Three-dimensional hot-spot reconstructions from x-ray measurements indicate that higher amounts of residual kinetic energy are correlated with higher measured hot-spot flow velocities, consistent with 3D simulations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2026

The Role of Three-dimensional Effects on Ion Injection and Acceleration in Perpendicular Shocks

Understanding the conditions that enable particle acceleration at nonrelativistic collisionless shocks is essential to unveil the origin of cosmic rays. We employ 2D and 3D hybrid simulations (with kinetic ions and fluid electrons) to explore particle acceleration and magnetic field amplification in nonrelativistic perpendicular shocks, focusing on the role of shock drift acceleration and its dependence on the shock Mach number. We perform an analysis of the ion injection process and demonstrate why efficient acceleration is only observed in 3D. In particular, we show that ion injection critically depends on the “porosity” of the magnetic turbulence in the downstream region near the shock, a property describing how easily the postshock region allows particles to traverse it and return upstream without being trapped. This effect can only be properly captured in 3D. Additionally, we explore the impact of numerical resolution on ion energization, highlighting how resolving small-scale turbulence—on scales below the thermal ion gyroradius—is essential for accurately modeling particle injection. Overall, our results emphasize the necessity of high-resolution 3D simulations to capture the fundamental microphysics driving particle acceleration at perpendicular shocks.

Orusa, Luca [Princeton Univ., NJ (United States); ↗

NASA NTRSDate not supplied

Characterization of Dendritic Spatially Extended 3D Patterns in Directional Solidification: Microgravity Experiments in DECLIC-DSI onboard ISS and 3D Phase-field Simulations

To clarify and characterize the fundamental physical mechanisms active in the dynamical formation of three-dimensional (3D) arrays of dendrites under diffusive growth conditions, in situ monitoring of series of experiments on transparent model alloy succinonitrile – 0.46 wt% camphor was carried out under low gravity in the DECLIC Directional Solidification Insert onboard the International Space Station. These experiments offer the very unique opportunity to observe in situ and characterize the dynamics of the microstructure formation and evolution in extended 3D patterns under microgravity environment. The analyses of the dendritic patterns for a broad range of growth velocities displaying different levels of sidebranching will be presented. Especially, the time evolution of primary spacing, in case of solidifications at constant pulling rate as well as for experiments with pulling rate jump, will be compared to 3D phase-field simulations, and the results will be discussed in terms of stable spacing range.

Kaihua Ji↗

NASA NTRSDate not supplied

Characterization of Dendritic Spatially Extended 3D Patterns in Directional Solidification: Microgravity Experiments in DECLIC-DSI Onboard ISS and 3D Phase-field Simulations

Kaihua Ji↗

DOE OSTI2017

Natural convection in a cubical cavity with a coaxial heated cylinder

High-resolution three-dimensional simulations were conducted to investigate the velocity and temperature fields in a cold cubical cavity due to natural convection induced by a centrally placed hot cylinder. Unsteady, incompressible Navier-Stokes equations were solved by using a spectral- element method for Rayleigh numbers ranging from 10 3 to 10 9 . The effect of spanwise thermal boundary conditions, aspect ratio (radius of the cylinder to the side of the cavity), and spanwise temperature distribution of the inner cylinder on the velocity and thermal fields were investigated for each Rayleigh number. Results from two-dimensional calculations were compared with three-dimensional simulations. The 3D results indicate a complex flow structure in the vicinity of the spanwise walls. The results also show that the imposed thermal wall boundary condition impacts the flow and temperature fields strongly near the spanwise walls. The variation of the local Nusselt number on the cylinder surface and enclosure walls at various spanwise locations was also investigated. The local Nusselt number on the cylinder surface and enclosure walls at the cavity mid-plane (Z = 0) is close to 2D simulations for 10 3 ≤ Ra ≤ 10 8 . Simulations also show a variation in the local Nusselt number, on both the cylinder surface and the enclosure walls, in the spanwise direction, for all Rayleigh numbers studied in this work. The results also indicate that if the enclosure walls are insulated in the spanwise direction (as opposed to a constant temperature), the peak Nusselt number on the enclosure surface occurs near the spanwise walls and is about 20% higher than the peak Nusselt number at the cavity mid-plane. The temporal characteristics of 3D flows are also different from 2D results for Ra > 10 8 . Furthermore, these results suggest that 3D simulations would be more appropriate for flows with Ra > 10 8 .

42 ENGINEERING↗

DOE OSTI2019

The Effect of Fault Geometry and Minimum Shear Wavespeed on 3D Ground-Motion Simulations for an M w 6.5 Hayward Fault Scenario Earthquake, San Francisco Bay Area, Northern California

We investigated the effects of fault geometry and assumed minimum shear wavespeed (V Smin ) on 3D ground-motion simulations (0–2.5 Hz) in general, using a moment magnitude (M w ) 6.5 earthquake on the Hayward fault (HF). Simulations of large earthquakes on the northeast-dipping HF using the U.S. Geological Survey (USGS) 3D seismic model have shown intensity asymmetry with stronger shaking for the Great Valley Sequence east of the HF (hanging wall) relative to the Franciscan Complex to the west (footwall). We performed simulations with three fault geometries in both plane-layered (1D) and 3D models. Results show that the nonvertical fault geometries result in larger motions on the hanging wall relative to the vertical fault for the same Earth model with up to 50% amplifications in single-component peak ground velocity (PGV) within 10 km of the rupture. Near-fault motions on the footwall are reduced for the nonvertical faults, but less than they are increased on the hanging wall. Simulations assuming V Smin values of 500 and 250 m/s reveal that PGVs are on average 25% higher west of the HF when using the lower V Smin ,with some locations amplified by a factor of 3. Increasing frequency content from 2.5 to 5 Hz increases PGV values. Spectral ratios of these two V Smin cases show average amplifications of 2–4 (0.5–1.5 Hz) for the lower V Smin west of the fault. Large differences (up to 2×) in PGV across the HF from previous studies persist even for the case with a vertical fault or V Smin of 250 m/s. We conclude that assuming a V Smin of 500 m/s underestimates intensities west of the HF for frequencies above 0.5 Hz, and that low upper crustal (depth <10 km) shear wavespeeds defined in the 3D model contribute most to higher intensities east of the HF.

58 GEOSCIENCES↗

NASA NTRS1993

Three-dimensional magnetohydrodynamics of the emerging magnetic flux in the solar atmosphere

The nonlinear evolution of an emerging magnetic flux tube or sheet in the solar atmosphere is studied through 3D MHD simulations. In the initial state, a horizontal magnetic flux sheet or tube is assumed to be embedded at the bottom of MHD two isothermal gas layers, which approximate the solar photosphere/chromosphere and the corona. The magnetic flux sheet or tube is unstable against the undular mode of the magnetic buoyancy instability. The magnetic loop rises due to the linear and then later nonlinear instabilities caused by the buoyancy enhanced by precipitating the gas along magnetic field lines. We find by 3D simulation that during the ascendance of loops the bundle of flux tubes or even the flux sheet develops into dense gas filaments pinched between magnetic loops. The interchange modes help produce a fine fiber flux structure perpendicular to the magnetic field direction in the linear stage, while the undular modes determine the overall buoyant loop structure. The expansion of such a bundle of magnetic loops follows the self-similar behavior observed in 2D cases studied earlier. Our study finds the threshold flux for arch filament system (AFS) formation to be about 0.3 x 10 exp 20 Mx.

Matsumoto, R.↗

DOE OSTI2023

Coupling of CTF and RELAP5-3D Within an Enhanced Fidelity Nuclear Power Plant Simulator

A robust and accurate multiphysics engineering simulator is being developed to model the core behavior and system response of pressurized water reactors. This simulator relies on the NESTLE and CTF computer codes to model the neutronics and thermal hydraulics (TH), respectively, inside the core on a nodal scale and on the Reactor Excursion and Leak Analysis Program—Three Dimensional (RELAP5-3D) to model the entire nuclear steam supply system. The RELAP5-3D model includes highly detailed nodalization and multidimensional flow modeling throughout the vessel. Previously, pin-resolved data generated via the Virtual Environment for Reactor Analysis core simulator were used to improve the accuracy of the NESTLE core predictions. The engineering simulator being developed as part of this work uses the 3KEYMASTER platform to couple the enhanced NESTLE model to a nodal-fidelity CTF model to balance run time with accuracy; NESTLE provides node-dependent powers to CTF, and CTF provides node-dependent coolant densities and fuel temperatures to NESTLE.An overlapping domain approach is used for the core TH in which RELAP5-3D provides core boundary conditions based on the system response and CTF provides a node-dependent coolant heating rate to the RELAP5-3D core solution. In the preliminary TH demonstration discussed in this paper, CTF and RELAP5-3D provided similar steady-state core predictions, indicating the hydraulic compatibility between the codes, as well as reasonable and expected behavior under hypothetical transient conditions. This provides an initial step in ongoing efforts toward a robust, multiscale TH/neutronics engineering simulator capability.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2014

Advanced Small Modular Reactors: Prototype Development Capabilities of 3D Spatial Interactions and Failures During Scenario Simulation

Computers have been used for 3D modeling and simulation, but only recently have computational resources been able to give realistic results in a reasonable time frame for large complex models. This report addressed the methods, techniques, and resources used to develop a prototype for using 3D modeling and simulation engine to improve risk analysis and evaluate reactor structures and components for a given scenario. The simulations done for this evaluation were focused on external events, specifically tsunami floods, for a hypothetical nuclear power facility on a coastline.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2020

Induced Current Detector Simulation

We describe simulations of a detector concept with small, low capacitance, pixels with pitch/thickness ratio on the order of 10. The simulation utilizes 2D and 3D TCAD simulations followed by a generic SPICE front-end model including noise and Landau fluctuations. We also investigate the properties of weighting fields of various geometries. We investigate whether the transient induced current signals can be used to improve pattern recognition and establish track angle.

43 PARTICLE ACCELERATORS↗

NASA NTRS2014

Verification of Loop Diagnostics

Many different techniques have been used to characterize the plasma in the solar corona: density-sensitive spectral line ratios are used to infer the density, the evolution of coronal structures in different passbands is used to infer the temperature evolution, and the simultaneous intensities measured in multiple passbands are used to determine the emission measure. All these analysis techniques assume that the intensity of the structures can be isolated through background subtraction. In this paper, we use simulated observations from a 3D hydrodynamic simulation of a coronal active region to verify these diagnostics. The density and temperature from the simulation are used to generate images in several passbands and spectral lines. We identify loop structures in the simulated images and calculate the loop background. We then determine the density, temperature and emission measure distribution as a function of time from the observations and compare with the true temperature and density of the loop. We find that the overall characteristics of the temperature, density, and emission measure are recovered by the analysis methods, but the details of the true temperature and density are not. For instance, the emission measure curves calculated from the simulated observations are much broader than the true emission measure distribution, though the average temperature evolution is similar. These differences are due, in part, to inadequate background subtraction, but also indicate a limitation of the analysis methods.

Winebarger, A.↗

DOE OSTI2016

Prediction of countercurrent flow limitation and its uncertainty in a PWR hot leg

In previous studies, we did small-scale air-water experiments for the hot leg and pressurizer surge line in a PWR and three-dimensional (3D) numerical simulations for PWR conditions to evaluate countercurrent flow limitation (CCFL) there, and we developed a one-dimensional (1D) prediction method to generalize prediction of CCFL in a piping system such as the hot leg and pressurizer surge line. In this study, we evaluated computation errors of the 1D prediction method in comparison with CCFL data in the PWR hot leg models with the diameter D and length L of D = 50-650 mm and L/D = 4.5-9.5, and then evaluated uncertainties of the 1D prediction method in comparison with 3D numerical simulations for PWR conditions with D = 750 mm and L/D = 8.6. We found the computation errors were within the difference of dC = ±0.05 for the CCFL constant of C = 0.63 in the correlation with the Wallis parameters, but the computation errors include experimental errors and they are not uncertainties for the PWR conditions. The total uncertainty of the 1D computations for the actual PWR hot leg (including effects of the diameter and fluid properties) was estimated to be dC = ±0.035. The CCFL correlation and its uncertainty of dC = ±0.035 derived from the 1D prediction method were very close to those previously obtained from CCFL data and 3D simulations (dC = ±0.03). (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

NASA NTRS1993

When clusters collide - A numerical Hydro/N-body simulation of merging galaxy clusters

A 3D numerical simulation of two merging clusters of galaxies, using a hybrid Hydro/N-body code, is presented. The hydrodynamics of the code is solved by an Eulerian finite difference method. Initial results disclose that the X-ray emission of the dominant cluster becomes elongated and broadened; heating occurs at the core of the dominant cluster as a result of multiple shocks, and high velocity gas motions within the intracluster medium. It is predicted that clusters which have undergone recent mergers and do not have cooling flows will have high peculiar gas velocities and that the shocks and turbulence generated during the merger may power cluster-wide radio halos. Prolonged high-velocity gas motions through the dominant cluster core possibly play a major role in the formation and shaping of wide-angle tailed radio sources associated with central dominant galaxies. The N-body component of the simulation reveals the subcluster to be dispersed as it passes through the dominant cluster.

Roettiger, Kurt↗

DOE OSTI2018

A 3D DLM/FD method for simulating the motion of spheres and ellipsoids under creeping flow conditions

We present in this article a novel distributed Lagrange multiplier/fictitious domain (DLM/FD) method for simulating fluid-particle interaction in three-dimensional (3D) Stokes flow. The methodology is validated by comparing the numerical results for a neutrally buoyant particle, of either spherical or prolate shape, with the associated Jeffrey's solutions for a simple shear flow. The results concerning two balls, interacting under creeping flow conditions in a bounded shear flow, are consistent with those available in the literature. We will discuss also the interactions of two balls in a bounded shear flow, when these balls are very close initially. For a prolate ellipsoid rotating in a shear flow under the sole effect of the particle inertia, shear plane tumbling is stable, while log-rolling is unstable. For two prolate ellipsoids interacting in a bounded shear flow, the results are similar to those for two balls if the major axes are initially orthogonal to the shear plane (a result not at all surprising considering that the intersections of the ellipsoids with the shear pane are circular).

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2014

Charge-exchange coupling between pickup ions across the heliopause and its effect on energetic neutral hydrogen flux

Pickup ions (PUIs) appear to play an integral role in the multi-component nature of the plasma in the interaction between the solar wind (SW) and local interstellar medium (LISM). Three-dimensional (3D) MHD simulations with a kinetic treatment for neutrals and PUIs are currently still not viable. In light of recent energetic neutral atom (ENA) observations by the Interstellar Boundary EXplorer, the purpose of this paper is to illustrate the complex coupling between PUIs across the heliopause (HP) as facilitated by ENAs using estimates of PUI properties extracted from a 3D MHD simulation of the SW-LISM interaction with kinetic neutrals. First, we improve upon the multi-component treatment of the inner heliosheath (IHS) plasma from Zank et al. by including the extinction of PUIs through charge-exchange. We find a significant amount of energy is transferred away from hot, termination shock-processed PUIs into a colder, 'freshly injected' PUI population. Second, we extend the multi-component approach to estimate ENA flux from the outer heliosheath (OHS), formed from charge-exchange between interstellar hydrogen atoms and energetic PUIs. These PUIs are formed from ENAs in the IHS that crossed the HP and experienced charge-exchange. Our estimates, based on plasma-neutral simulations of the SW-LISM interaction and a post-processing analysis of ENAs and PUIs, suggest the majority of flux visible at 1 AU from the front of the heliosphere, between ∼0.02 and 10 keV, originates from OHS PUIs, indicating strong coupling between the IHS and OHS plasmas through charge-exchange.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2022

A 1D–0D–3D coupled model for simulating blood flow and transport processes in breast tissue

In this work, we present mixed dimensional models for simulating blood flow and transport processes in breast tissue and the vascular tree supplying it. These processes are considered, to start from the aortic inlet to the capillaries and tissue of the breast. Large variations in biophysical properties and flow conditions exist in this system necessitating the use of different flow models for different geometries and flow regimes. In total, we consider four different model types. First, a system of 1D nonlinear hyperbolic partial differential equations (PDEs) is considered to simulate blood flow in larger arteries with highly elastic vessel walls. Second, we assign 1D linearized hyperbolic PDEs to model the smaller arteries with stiffer vessel walls. The third model type consists of ODE systems (0D models). It is used to model the arterioles and peripheral circulation. Finally, homogenized 3D porous media models are considered to simulate flow and transport in capillaries and tissue within the breast volume. Sink terms are used to account for the influence of the venous and lymphatic systems. Combining the four model types, we obtain two different 1D–0D–3D coupled models for simulating blood flow and transport processes: The first model results in a fully coupled 1D–0D–3D model covering the complete path from the aorta to the breast combining a generic arterial network with a patient specific breast network and geometry. The second model is a reduced one based on the separation of the generic and patient specific parts. The information from a calibrated fully coupled model is used as inflow condition for the patient specific sub-model allowing a significant computational cost reduction. Several numerical experiments are conducted to calibrate the generic model parameters and to demonstrate realistic flow simulations compared to existing data on blood flow in the human breast and vascular system. Moreover, we use two different breast vasculature and tissue data sets to illustrate the robustness of our reduced sub-model approach.

multiscale blood flow models↗

DOE OSTI2024

3D Ferroelectric Phase Field Simulations of Polycrystalline Multi‐Phase Hafnia and Zirconia Based Ultra‐Thin Films

Abstract HfO 2 – and ZrO 2 –based ferroelectric thin films have emerged as promising candidates for the gate oxides of next‐generation electronic devices. Recent work has experimentally demonstrated that a tetragonal/orthorhombic (t/o‐) phase mixture with partially in‐plane polarization can lead to negative capacitance (NC) stabilization. However, there is a discrepancy between experiments and the theoretical understanding of domain formation and domain wall motion in these multi‐phase, polycrystalline materials. Furthermore, the effect of anisotropic domain wall coupling on NC has not been studied so far. Here, 3D phase field simulations of HfO 2 – and ZrO 2 –based mixed‐phase ultra‐thin films on silicon are applied to understand the necessary and beneficial conditions for NC stabilization. It is found that smaller ferroelectric grains and a larger angle of the polar axis with respect to the out‐of‐plane direction enhances the NC effect. Furthermore, it is shown that theoretically predicted negative domain wall coupling even along only one axis prevents NC stabilization. Therefore, it is concluded that topological domain walls play a critical role in experimentally observed NC phenomena in HfO 2 – and ZrO 2 –based ferroelectrics.

30 DIRECT ENERGY CONVERSION↗