An Efficient Simulation Method for Distributed Lumped Fluid Networks

1977 ◽  
Vol 99 (1) ◽  
pp. 34-40 ◽  
Author(s):  
R. S. Sidell ◽  
D. N. Wormley
Keyword(s):  
Finite Difference Methods ◽  
Computation Time ◽  
Simulation Method ◽  
Transmission Network ◽  
Efficient Simulation ◽  
Fluid Networks ◽  
Lumped Elements ◽  
Simulation Results ◽  
Core Storage ◽  
Nonlinear Resistance

A method is presented for the simulation of fluid networks consisting of uniform distributed elements and lumped dynamic, nonlinear elements. The uniform transmission elements may be lossy and dispersive. General relationships are derived for their terminations in junctions with other elements and/or with dynamic, nonlinear lumped elements. The basic computer simulation method is efficient in terms of computation time and core storage requirements in comparison to direct finite difference methods and may be implemented on a minicomputer. Simulation results are compared with experimental data for a pneumatic transmission line terminated with a nonlinear resistance and for a pneumatic transmission network consisting of three lines of incommensurate lengths.

IR Model of 3D Aircraft for Simulation of Reticle Seekers

1997 ◽  
Vol 07 (04) ◽  
pp. 333-344 ◽  
Author(s):  
Hyun-Ki Hong ◽  
Sung-Hyun Han ◽  
Gyoung-Pyo Hong ◽  
Surng-Gabb Jahng ◽  
Jong-Soo Choi
Keyword(s):  
Heat Source ◽  
Atmospheric Turbulence ◽  
Optical System ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Simulation Method ◽  
Thermal Images ◽  
Efficient Simulation ◽  
Infra Red ◽  
Simulation Results

This paper presents an efficient simulation method that generates thermal images and also gives tracking results of infra-red (IR) reticle seekers. First, we make an IR model of the object with the internal heat source, and generate thermal images by the optical system of the reticle seeker and the atmospheric turbulence. Using the obtained thermal images, we can simulate IR reticle seekers in various scenarios including countermeasures (CM) such as flares. Simulation results show that we can generate more accurate images by using the proposed method, which is applicable to the study of the development of counter-countermeasures (CCMs).

Application of Backus average to simulate acoustic logs in thinly bedded formations

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. D93-D104
Author(s):  
Elsa Maalouf ◽  
Carlos Torres-Verdín ◽  
Jingxuan Li
Keyword(s):  
Finite Difference ◽  
Numerical Simulations ◽  
Finite Difference Methods ◽  
Homogeneous Medium ◽  
Computation Time ◽  
Transversely Isotropic ◽  
Simulation Method ◽  
Thin Layers ◽  
Homogeneous Layer ◽  
Spatial Averaging

Slowness logs acquired in layered formations are not only affected by spatial averaging associated with the borehole acoustic tool. Layers with thicknesses smaller than the acoustic wavelength can cause measurable effects on the associated wave propagation phenomena. While spatial averaging functions can be used to model tool averaging effects, computer-intensive numerical methods such as finite differences must be used to simulate slowness logs across formations with thin layers. We adopted Backus averaging as a faster alternative to model borehole slownesses when layer thicknesses are smaller than the acoustic wavelength (i.e., in the long-wavelength limit). Using synthetic models and numerical simulations via finite-element and finite-difference methods, we have determined that borehole slownesses of a stack of horizontal layers first approach the average slowness of the individual layers. However, as the layer thickness decreases, sonic slownesses approach the slowness of a homogeneous medium with elastic properties obtained from the Backus average. Therefore, to model acoustic logs acquired in layered formations, we first approximate thin layers as a single homogeneous layer with stiffness coefficients calculated using the Backus average. Next, we apply a spatial averaging function to reproduce the spatial averaging effect inherent to borehole acoustic tools. Results indicate that the latter method is accurate and efficient for fast modeling borehole slownesses of formations with thin layers that are isotropic and intrinsically vertical transversely isotropic. The fast simulation method decreases computation time by at least a factor of 10 and yields slowness logs with a relative error below 2% compared with finite-difference numerical simulations. We also determine that the moving Backus average that is typically applied to upscale acoustic logs for seismic applications is not accurate to model borehole acoustic logs acquired across thinly layered formations.

Study of HVDC System and Subsynchronous Oscillation

2015 ◽  
Vol 1092-1093 ◽  
pp. 356-361
Author(s):  
Peng Fei Zhang ◽  
Lian Guang Liu
Keyword(s):  
Power Plant ◽  
Time Domain ◽  
Simulation Method ◽  
Time Domain Simulation ◽  
Stable Convergence ◽  
Turbine Generator ◽  
Plant Model ◽  
Subsynchronous Oscillation ◽  
Hvdc System ◽  
Simulation Results

With the application and development of Power Electronics, HVDC is applied more widely China. However, HVDC system has the possibilities to cause subsynchronous torsional vibration interaction with turbine generator shaft mechanical system. This paper simply introduces the mechanism, analytical methods and suppression measures of subsynchronous oscillation. Then it establishes a power plant model in islanding model using PSCAD, and analyzes the effects of the number and output of generators to SSO, and verifies the effect of SEDC and SSDC using time-domain simulation method. Simulation results show that the more number and output of generators is detrimental to the stable convergence of subsynchronous oscillation, and SEDC、SSDC can restrain unstable SSO, avoid divergence of SSO, ensure the generators and system operate safely and stably

A Reformative Simulation Method of Motor Pole Core Vibration Characteristics

2013 ◽  
Vol 331 ◽  
pp. 118-123
Author(s):  
Tian Hui Ding ◽  
Yun Hua Chen ◽  
Lei Tian
Keyword(s):  
Reference Value ◽  
Simulation Method ◽  
Vibration Characteristics ◽  
New Method ◽  
Motor Design ◽  
Simulation Results ◽  
Vibration Performance

As to directing motor design, it is very important to make sure that the motor’s forecast of vibration performance has reference value. So, it must need motor’s parts vibration characteristics simulation results are so close to their characteristics. This paper puts forward a new simulation method of motor pole core vibration characteristics, this method includes setting anisotropy material attributes multipartite, getting attributes parameters values which are based on recommended fitting curves, modeling and equating windings, equating dipping lacquer and so on. Combining with experiments, the new method is validated its availability.

Efficient Simulation Method to Predict Green Water Loads on Superstructures

2015 ◽  
Author(s):  
Lasse Theilen ◽  
Ole Detlefsen ◽  
Moustafa Abdel-Maksoud ◽  
Michael Bohm
Keyword(s):  
Simulation Method ◽  
Computational Effort ◽  
Numerical Prediction ◽  
Green Water ◽  
Impact Loads ◽  
Operational Conditions ◽  
Efficient Simulation ◽  
Non Linear ◽  
Linear Behaviour

The numerical prediction of green water loads on super-structures is challenging due to the high number of required calculations to identify the critical operational conditions in the seaway which lead to overcoming seawater on deck. Further, the simulation of the non-linear behaviour of water on the deck and the prediction of impact loads require high computational effort. This paper presents an efficient three-step approach to simulate green water loads. The application of the developed procedure will be demonstrated on a mega yacht geometry.

Simulation Investigation of Tangential-Feed Centerless Grinding Process Performed on Surface Grinder

2009 ◽  
Vol 626-627 ◽  
pp. 23-28
Author(s):  
Wei Xing Xu ◽  
Yong Bo Wu ◽  
Takashi Sato ◽  
Wei Min Lin
Keyword(s):  
Elastic Deformation ◽  
Process Parameters ◽  
Simulation Method ◽  
Machining Accuracy ◽  
Grinding Process ◽  
Elasticity Parameter ◽  
Grinding Method ◽  
Centerless Grinding ◽  
Simulation Results ◽  
Grinding Technique

In our previous study, a new centerless grinding method using surface grinder was proposed. This paper describes a simulation method for investigating the workpiece rounding process in which a model taking the elastic deformation of the machine into consideration is created, and revealing how the process parameters affect the machining accuracy in the new grinding technique. In addition, a practice way to determine the machining-elasticity parameter showing the elastic deformation is developed. The simulation results are compared to show the effect of process parameters on the machining accuracy.

Numerical Simulation of the Stress Field of Thick 7B04 Aluminum Alloy Board during Continuous Manufacture Procedure

2007 ◽  
Vol 127 ◽  
pp. 259-264
Author(s):  
Hong Yuan Fang ◽  
Cheng Iei Fan
Keyword(s):  
Numerical Simulation ◽  
Aluminum Alloy ◽  
Stress Concentration ◽  
Stress Field ◽  
Solution Treatment ◽  
Simulation Method ◽  
The Core ◽  
Manufacturing Procedure ◽  
Continuous Manufacture ◽  
Simulation Results

Numerical simulation method is employed in the article to analyze the stress field of thick 7B04 aluminum alloy board during manufacturing procedure of solution treatment, calendaring and stretching. The simulation results show that the surface of the board endures compressive stress while the core segment endures tensile stress, and the distribution of the stress is very inhomogeneous. The calendaring procedure helps to decrease the stress and redistribute the stress uniformly, but it also leads to stress concentration at the two ends of the board, which engenders bad influence on the subsequent processing. The board deforms plastically when being stretched, thus the stress decreases greatly and is redistributed uniformly.

scholarly journals Numerical Simulation Study on the Front Shape and Thermal Stresses in Growing Multicrystalline Silicon Ingot: Process and Structural Design

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1053
Author(s):  
Chengmin Chen ◽  
Guangxia Liu ◽  
Lei Zhang ◽  
Guodong Wang ◽  
Yanjin Hou ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Simulation Method ◽  
Power Ratio ◽  
Radial Temperature ◽  
Front Shape ◽  
Simulation Results ◽  
Insulation Block ◽  
Transient Numerical Simulation

In this paper, a transient numerical simulation method is used to investigate the effects of the two furnace configurations on the thermal field: the shape of the melt–crystal (M/C) interface and the thermal stress in the growing multicrystalline ingot. First, four different power ratios (top power to side power) are investigated, and then three positions (i.e., the vertical, angled, and horizontal positions) of the insulation block are compared with the conventional setup. The power ratio simulation results show that with a descending power ratio, the M/C interface becomes flatter and the thermal stress in the solidified ingot is lower. In our cases, a power ratio of 1:3–1:4 is more feasible for high-quality ingot. The block’s position simulation results indicate that the horizontal block can more effectively reduce the radial temperature gradient, resulting in a flatter M/C interface and lower thermal stress.

scholarly journals An Assessment of Quantitative Predictions of Deterministic Mixed Lubrication Solvers

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Yuechang Wang ◽  
Abdel Dorgham ◽  
Ying Liu ◽  
Chun Wang ◽  
Mark C. T. Wilson ◽  
...  
Keyword(s):  
Reynolds Equation ◽  
Thickness Distribution ◽  
Computation Time ◽  
Simulation Method ◽  
Coefficient Matrix ◽  
Mixed Lubrication ◽  
Contact Ratio ◽  
Lubricated Contacts ◽  
Discretization Schemes ◽  
Parametric Studies

Abstract The ability to simulate mixed lubrication problems has greatly improved, especially in concentrated lubricated contacts. A mixed lubrication simulation method was developed by utilizing the semi-system approach which has been proven to be highly useful for improving stability and robustness of mixed lubrication simulations. Then different variants of the model were developed by varying the discretization schemes used to treat the Couette flow terms in the Reynolds equation, varying the evaluation of density derivatives and varying the contribution of terms in the coefficient matrix. The resulting pressure distribution, film thickness distribution, lambda ratio, contact ratio, and the computation time were compared and found to be strongly influenced by the choice of solution scheme. This indicates that the output from mixed lubrication solvers can be readily used for qualitative and parametric studies, but care should be taken when making quantitative predictions.

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