scholarly journals Three‐Dimensional Distribution of Groundwater Residence Time Metrics in the Glaciated United States Using Metamodels Trained on General Numerical Simulation Models

2021 ◽  
Vol 57 (2) ◽  
Author(s):  
J. J. Starn ◽  
L. J. Kauffman ◽  
C. S. Carlson ◽  
J. E. Reddy ◽  
M. N. Fienen
Keyword(s):  
United States ◽  
Numerical Simulation ◽  
Residence Time ◽  
Three Dimensional ◽  
Simulation Models ◽  
Dimensional Distribution ◽  
Groundwater Residence Time

Study on flight safety manipulation space under complex conditions

2018 ◽  
Vol 233 (2) ◽  
pp. 725-735 ◽  
Author(s):  
Zhe Li ◽  
Haojun Xu ◽  
Yuan Xue ◽  
Binbin Pei
Keyword(s):  
Situational Awareness ◽  
Complex Dynamics ◽  
Three Dimensional ◽  
Simulation Models ◽  
Flight Simulation ◽  
Flight Safety ◽  
Flight Data ◽  
Dimensional Distribution ◽  
Aircraft Performance ◽  
Engine Failure

This study considers the situational awareness under complex conditions like aircraft failures or adverse environments. To enhance pilot’s situational awareness, flight safety manipulation space is proposed based on risk prediction. Current methods normally predict the occurrence of accidents by estimating whether the safety-related parameters exceed their limitations. The complex dynamics of pilot–vehicle–environment simulation models are built and the safety-related flight data are represented by risk colors according to their limits. The safety spectrum is then obtained by the integration of the flight data under a certain manipulation action, and the colored risk value for the single flight condition is further acquired. The colored two-dimensional and three-dimensional distribution topology maps can be calculated by a parallel flight simulation platform. The flight safety manipulation space for one-side engine failure and main surface jams are researched and the disaster-causing mechanism is analyzed. Simulation results show that the outbreak failure may lead to the shrink and even distortion of the safety manipulation space. The proposed method could provide a theoretical support for pilots to enhance situational awareness under complex adverse conditions, an engineering tool for aircraft designers to optimize the aircraft performance, and a visualization analysis method to reveal the accident evolution.

Development of Numerical Simulation Method for Melt Relocation Behavior in Nuclear Reactors: Validation of Applicability for Actual Core Support Structures

2016 ◽  
Author(s):  
Susumu Yamashita ◽  
Kazuyuki Tokushima ◽  
Masaki Kurata ◽  
Kazuyuki Takase ◽  
Hiroyuki Yoshida
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
Computer Aided Design ◽  
Nuclear Power ◽  
Radiation Heat Transfer ◽  
Three Dimensional ◽  
Simulation Models ◽  
Simulation Method ◽  
Transfer Model ◽  
Simulation Code

In order to precisely investigate molten core relocation behavior in the Fukushima Daiichi nuclear power station, we have developed the detailed and phenomenological numerical simulation code named JUPITER for predicting the molten core behavior including solidification and relocation based on the three-dimensional multiphase thermal-hydraulic simulation models. At the moment, multicomponent analysis method which can be treated any number of component as a fluid or solid body, Zr-water reaction model and simple radiation heat transfer model were implemented and showed that multicomponent melt flow and its solidification were confirmed in the simplified core structure system. However, the validation of the JUPITER using high temperature molten material has not been performed yet. In this paper, in order to evaluate the validity of the JUPITER, especially, for high temperature melt relocation experiment, we compared between numerical and experimental results for that system. As a result, qualitatively reasonable result was obtained. And also we performed melt relocation simulation on actual core structures designed by three dimensional CAD (Computer-Aided Design) and then we estimated phenomena which might be actually occurred in SAs.

Numerical Simulation of Ultrasonic-Assisted Grinding Surfaces With Fast Fourier Transform

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Lin Li ◽  
Jinyuan Tang ◽  
Yuqin Wen ◽  
Caichao Zhu
Keyword(s):  
Numerical Simulation ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Autocorrelation Function ◽  
Three Dimensional ◽  
Simulation Models ◽  
Research Focus ◽  
Ultrasonic Assisted Grinding ◽  
Ultrasonic Assisted ◽  
First Time

Abstract Numerical simulation of three-dimensional rough surfaces based on fast Fourier transform (FFT) is revisited. A more systematic approach, which is an extension of the current FFT-based simulation models, is proposed to approach surface reconstruction. Moreover, the simulation of the surfaces with machining signature by prescribing the parameters, take ultrasonic-assisted grinding as an example, has been taken as the research focus for the first time. The effectiveness is tested by three cases of simulation examples. Excepting the surface with exponential autocorrelation function, the simulation of surfaces with grinding machining marks is considered both by prescribing the theory autocorrelation function and by measuring a small area as a sample. The results show that the proposed method has great potential in engineering applications.

scholarly journals Numerical Analysis of the Pivot Node in Fracture Problems

2018 ◽  
Vol 774 ◽  
pp. 473-478
Author(s):  
J. Garcia-Manrique ◽  
Daniel Camas ◽  
A. Lima-Rodriguez ◽  
Antonio González-Herrera
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Load Level ◽  
Mode I ◽  
Ansys Software ◽  
Narrow Region ◽  
Factors Influencing ◽  
Experimental Correlation ◽  
Dimensional Distribution ◽  
Main Factors

Recent studies have allowed us to identify a narrow region of the thickness of the crack front in fracture problems that presents interesting characteristics for the numerical-experimental correlation. Taking the three-dimensional distribution of the stress intensity factor (K) as a reference, we observe how it remains invariant and independent of the main factors influencing this type of analysis. This article presents a summary of how to identify this point through the numerical simulation of the problem and its relationship with parameters such as thickness, load level or angle of curvature. The simulations are carried out with the ANSYS software in an aluminium CT specimen subjected to a fracture loading process in mode I.

Computational Investigation of Full-Scale Tethered Underwater Kite

2018 ◽  
Author(s):  
Amirmahdi Ghasemi ◽  
David J. Olinger ◽  
Gretar Tryggvason
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Simulation Models ◽  
Slip Boundary Condition ◽  
Full Scale ◽  
Grid Resolution ◽  
Ocean Current ◽  
Computational Domain ◽  
Fixed Structure

In this paper, a numerical simulation of three-dimensional motion of tether undersea kites (TUSK) for power generation is studied. TUSK systems includes a rigid-winged kite, or glider, moving in an ocean current in which a tethered kite is connected by a flexible tether to a fixed structure. Kite hydrodynamic forces are transmitted through the tether to an electrical generator on the fixed structure. The numerical simulation models the flow field in a three-dimensional domain near the rigid undersea kite wing by solving the full Navier-Stokes equations. In order to resolve the boundary layer near the kite surface, adequate grid resolution is needed which increases the computational run time drastically especially in 3D simulations. Therefore, in this study a slip boundary condition is implemented at the kite interface to accurately predict the total drag, with lower grid resolution. In order to reduce the numerical run times, a moving computational domain method is also used. A PID controller is used to adjuste the kite pitch, roll and yaw angles during power (tether reel-out) and retraction (reel-in) phases. A baseline simulation study of a full-scale TUSK system is conducted in which the expected cross-current, figure-8 motions during a kite reel-out phase is captured. The effect of the tether drag on the kite motion and resulting power output is also investigated and compared with the results of the baseline simulation.

scholarly journals A novel method for objective identification of 3-D potential vorticity anomalies

2022 ◽  
Author(s):  
Christoph Fischer ◽  
Andreas H. Fink ◽  
Elmar Schömer ◽  
Roderick van der Linden ◽  
Michael Maier-Gerber ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Case Studies ◽  
Potential Vorticity ◽  
Three Dimensional ◽  
Simulation Models ◽  
Atmospheric Dynamics ◽  
Precipitation Event ◽  
Efficient Computation ◽  
Morphological Image Processing

Abstract. Potential vorticity (PV) analysis plays a central role in studying atmospheric dynamics and in particular in studying the life cycle of weather systems. The three-dimensional (3-D) structure and temporal evolution of the associated PV anomalies, however, are not yet fully understood. An automated technique to objectively identify 3-D PV anomalies can help to shed light on 3-D atmospheric dynamics in specific case studies, as well as facilitate statistical evaluations within climatological studies. Such a technique to identify PV anomalies fully in 3-D, however, does not yet exist. This study presents a novel algorithm for the objective identification of PV anomalies in gridded data, as commonly output by numerical simulation models. The algorithm is inspired by morphological image processing techniques and can be applied to both two-dimensional (2-D) and 3-D fields on vertically isentropic levels. The method maps input data to a horizontally stereographic projection and relies on an efficient computation of horizontal distances within the projected field. Candidates for PV anomaly features are filtered according to heuristic criteria, and feature description vectors are obtained for further analysis. The generated feature descriptions are well suited for subsequent case studies of 3-D atmospheric dynamics as represented by the underlying numerical simulation, or for generation of climatologies of feature characteristics. We evaluate our approach by comparison with an existing 2-D technique, and demonstrate the full 3-D perspective by means of a case study of an extreme precipitation event that was dynamically linked to a prominent subtropical PV anomaly. The case study demonstrates variations in the 3-D structure of the detected PV anomalies that would not have been captured by a 2-D method. We discuss further advantages of using a 3-D approach, including elimination of temporal inconsistencies in the detected features due to 3-D structural variation, and elimination of the need to manually select a specific isentropic level on which the anomalies are assumed to be best captured. The method is made available as open-source for straightforward use by the atmospheric community.

Development of Numerical Simulation Method for Relocation Behavior of Molten Debris in Nuclear Reactors: 1 — Preliminary Analysis of Relocation of Molten Debris to Lower Plenum

2013 ◽  
Author(s):  
Susumu Yamashita ◽  
Hiroyuki Yoshida ◽  
Kazuyuki Takase
Keyword(s):  
Numerical Simulation ◽  
Solid Phase ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Simulation Models ◽  
Simulation Method ◽  
Melting Behavior ◽  
Hydraulic Simulation ◽  
Numerical Simulation Method ◽  
Two Phases

We developed the numerical simulation method for predicting the melting core behavior including solidification and relocation based on the three-dimensional multi-phase thermal-hydraulic simulation models. In this code, each of gas, liquid and solid phase are treated individually, and interface between two phases are simulated directly. In this paper, the developed code was applied to numerical simulations of the melting behavior of the simulated fuel assemblies and reactor structures. In the simulation, complicated structures in the BWR lower plenum was simply modeled. A decay heat in molten or solidified debris was also considered. Moreover, several different initial conditions were used to check performance of this code and to evaluate adequacy of the present numerical method. From the present numerical results, it was confirmed that relocation of molten debris in the BWR lower plenum can be simulated by the currently developed code including effects of melting and solidification of debris.

Simulation of Tethered Underwater Kites: Three Dimensional Trajectories for Power Generation

2016 ◽  
Author(s):  
Amirmahdi Ghasemi ◽  
David J. Olinger ◽  
Gretar Tryggvason
Keyword(s):  
Numerical Simulation ◽  
Power Generation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Simulation Models ◽  
Hydrodynamic Forces ◽  
Ocean Current ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Flow Equations

In this paper, a numerical simulation of three dimensional motion of tether undersea kites (TUSK) for power generation is studied. TUSK systems consist of a rigid-winged kite, or glider, moving in an ocean current. One proposed concept uses a tethered kite which is connected by a flexible tether to a support structure with a generator on the ocean surface. The numerical simulation models the flow field in a three-dimensional domain near the rigid undersea kite wing by solving the full Navier-Stokes equations. A two-step projection method along with Open Multi-Processing (OpenMP) is employed to solve the flow equations. In order to track the rigid kite, an immersed boundary method is used. A NACA 0021 airfoil is used for the cross section shape of the kite, and the tension forces in the elastic tethers are modeled by a simple Hooke’s law. A grid refinement study has been carried out to ensure the independence of the numerical results on the grid mesh resolution. Also, the Reynolds number independency has been studied. PID control methods are used to adjust the kite pitch, roll and yaw angles during power (tether reel-out) and retraction (reel-in) phases to obtain desired kite trajectories. During the reel-out phase the kite moves in successive cross-current motions in a figure-8 pattern, the tether length increases and power is generated. During reel-in the kite motion is along the tether, and kite hydrodynamic forces are reduced so that net positive power is produced. Kite trajectories, hydrodynamic forces on the kite, kite tether tension and output power are determined and analyzed for a baseline TUSK simulation.

Numerical Simulation and Optimization of Air Distribution in Large Space

2014 ◽  
Vol 1070-1072 ◽  
pp. 2021-2026
Author(s):  
Ze Hang Du ◽  
Chun Hua Liu ◽  
Guang Zhou
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Large Space ◽  
Air Conditioning System ◽  
Simulation And Optimization ◽  
Air Inlet ◽  
Air Supply ◽  
Dimensional Distribution ◽  
Air Speed

In recent years, people pay increasing attention to the issue whether indoor air conditioning system can meet the requirements of thermal comfort under the circumstance of good air quality and reduce energy consumption. FLUENT, commercial computational fluid dynamics software is used to simulate the three-dimensional distribution of temperature and velocity in the subject hotel atrium. The turbulence model modified by buoyancy was used to solve equations. The SIMPLE scheme was used for numerical discrimination. Distribution of temperature, velocity on some typical section and the atrium space can be obtained; the result of numerical simulation can be visualized by post-processing module of FLUENT and TECPLOT software. The influence to the air flow distribution is simulated and calculated by the elements of different rates, angle, and height of the air supply flow. As for the specified case of the project, an optimized solution is obtained, that is supply air speed 6 m/s, angle 15°, air inlet height 7.5m, air temperature 291K.

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