Initial Condition and Calculation Method for the Numerical Simulation of LPE

2007 ◽  
Vol 40 (11) ◽  
pp. 928-938
Author(s):  
Hiromoto Susawa ◽  
Toshihiro Tsuji ◽  
Takashi Jimbo ◽  
Tetsuo Soga
Keyword(s):  
Numerical Simulation ◽  
Calculation Method ◽  
Initial Condition

The Calculation Method of Accurate Shaping Curve of Inside Right-Angle Step in Cross Wedge Rolling

2010 ◽  
Vol 37-38 ◽  
pp. 1416-1420 ◽  
Author(s):  
Ran Zhao ◽  
Kang Sheng Zhang ◽  
Zheng Huan Hu
Keyword(s):  
Numerical Simulation ◽  
Mathematical Models ◽  
Contact Zone ◽  
Calculation Method ◽  
Cross Wedge Rolling ◽  
Forming Process

Deep study on Inside Right-angle Step (IRS) forming process was conducted to improve the precision of its (IRS) forming. According to its actual forming process, the zone, or the undeformed zone, was looked as semi-spiral declined cone and excluded the contact zone. A new algorithm was developed for calculating the size of the undeformed zone. More simple mathematical models and expressions weredeveloped for solving the shaping curve. The model was verified in terms of its simplicity and correctness based on the numerical simulation.

The Research of Calculation Method on Vertical Natural Frequency of the New Full-Prefabricated Floor

2016 ◽  
Vol 846 ◽  
pp. 506-511
Author(s):  
Chong Fang Sun ◽  
Shu Ting Liang ◽  
Xiao Jun Zhu
Keyword(s):  
Numerical Simulation ◽  
Natural Frequency ◽  
Calculation Method ◽  
Variable Stiffness ◽  
Series Method ◽  
Numerical Simulation Result ◽  
Stiffness Method ◽  
Calculation Results ◽  
New Type ◽  
Test Result

New-type floor is composed of three kinds of slabs joined together through fittings. It is a kind of anisotropic two-way slab. In order to study the calculation method of natural frequency, series method, variable thickness method and variable stiffness method are adopted to calculate the natural frequency. The calculation results of three methods are compared with test result and numerical simulation result. The conclusion is that the calculation result of the variable stiffness method is the closest to the real natural frequency of new-type floor.

Predicting lean blow-off limit of gas turbine combustors based on Damköhler number and detailed atomization information

2020 ◽  
pp. 095765092092003
Author(s):  
Zhonghao Wang ◽  
Bin Hu ◽  
Aibing Fang ◽  
Aiming Deng ◽  
Junhua Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Gas Turbine ◽  
Calculation Method ◽  
Time Scale ◽  
Prediction Accuracy ◽  
Drop Size ◽  
Prediction Method ◽  
Negative Effects ◽  
Supply Pressure ◽  
Uniform Model

A hybrid lean blow-off prediction method based on Damköhler ( Da) number was proposed in the authors’ previous study. However, the uniform model for fuel drop size distribution cannot fully reflect the actual atomization quality under lean blow-off conditions, which has negative effects on prediction accuracy. In the current study, atomization experiments are conducted under different fuel supply pressure. The atomization quality is described by Rosin–Rammler model and is integrated into numerical simulation. The calculation method of chemical time scale ( τc) is improved by accurately differentiating the inlet and outlet surface of reaction zone. After the improvement, the Da number under lean blow-off conditions mainly lies between 0.3 and 0.8, while under the designing condition, the Da number is about 20. Compared with the former method, the optimized method in the present article can distinguish stable combustion states markedly from lean blow-off states. Through the introduction of detailed atomization information and the improvement of time scale calculation, lean blow-off prediction accuracy in the present work is efficiently improved, which can provide powerful technical support for engineering applications.

scholarly journals Buried Depth of a Submarine Pipeline Based on Anchor Penetration

2019 ◽  
Vol 7 (8) ◽  
pp. 257
Author(s):  
Xueyuan Zhu ◽  
Qinglong Hao ◽  
Jie Zhang
Keyword(s):  
Numerical Simulation ◽  
Penetration Depth ◽  
Water Depth ◽  
Calculation Method ◽  
Water Surface ◽  
Submarine Pipeline ◽  
Projected Area ◽  
Actual Measurement ◽  
Calculation Results ◽  
The Relationship

Anchor penetration is an important issue involved in the study of submarine pipeline damage accidents. To explore the penetration of a ship’s anchor under certain conditions, this study investigated the motion and force of an anchor and formulated a calculation method for the bottoming speed of an anchor. Meanwhile, the depth of anchor penetration was calculated under different conditions according to bottoming speed through programming. Finally, the reliability of the calculation method for the penetration depth was verified by comparing the actual measurement and the numerical simulation. On the basis of the findings, the calculation results were further analyzed, and conclusions were derived regarding the relationship between anchor mass, the horizontal projected area of the anchor, the anchor height on the water surface, and water depth. The conclusions provide suggestions for the application of anchor penetration in terms of seabed depth with certain reference values.

scholarly journals Application of Pontryagin’s Minimum Principle in Optimum Time of Missile Manoeuvring

CAUCHY ◽  
2016 ◽  
Vol 4 (3) ◽  
pp. 107
Author(s):  
Sari Cahyaningtias ◽  
Subchan Subchan
Keyword(s):  
Numerical Simulation ◽  
Minimum Principle ◽  
Terminal Velocity ◽  
Initial Condition ◽  
Pontryagin’S Minimum Principle ◽  
Fixed Target ◽  
Optimum Time ◽  
Self Defense ◽  
Pontryagin's Minimum Principle ◽  
Aerial Vehicle

Missile is a guided weapon and designed to protect outermost island from a thread of other country. It, commonly, is used as self defense. This research presented surface-to-surface missile in final dive manoeuvre for fixed target. Furthermore, it was proposed manoeuvring based on unmanned aerial vehicle (UAV), autopilot system, which needs accuration and minimum both time and thrust of missile while attacking object. This paper introduced pontryagin’s Minimum Principle, which is useable to solve the problem. The numerical solution showed that trajectory of the missile is split it up in three sub-intervals; flight, climbing, and diving. The numerical simulation showed that the missile must climb in order to satisfy the final dive condition and the optimum time of a missile depend on initial condition of the altitude and the terminal velocity

Energy of a tsunami in the framework of an irreversible deformation of the ocean bottom

2020 ◽  
Author(s):  
Emile Okal ◽  
Costas Synolakis
Keyword(s):  
Numerical Simulation ◽  
Exact Analytical Solution ◽  
Source Area ◽  
Ocean Bottom ◽  
Generation Process ◽  
Initial Condition ◽  
Tsunami Simulation ◽  
Earthquake Sources ◽  
A Value ◽  
Classic Approach

<p>The classic approach to tsunami simulation by earthquake sources consists<br>of computing the vertical static deformation of the ocean bottom due to<br>the dislocation, using formalisms such as Mansinha and Smylie's [1971] or<br>Okada's [1985], and of transposing that field directly to the ocean's<br>surface as the initial condition of the numerical simulation.<br>We look into the limitations of this approach by developing a very<br>simple general formula for the energy of a tsunami, expressed as the<br>work performed against the hydrostatic pressure at the bottom of<br>the ocean, in excess of the simple increase in potential energy<br>of the displaced water, due to the irreversibility of the process.<br>We successfully test our results against the exact analytical solution<br>obtained by Hammack [1972] for the amplitude of a tsunami generated<br>by the exponentially-decaying uplift of a circular plug on the ocean<br>bottom. We define a "tsunami efficiency" by scaling the resulting energy<br>to its classical value derived, e.g., by Kajiura [1963]. As expected, we<br>find that sources with shorter rise times are more efficient tsunami<br>generators; however, an important new result is that the efficiency is<br>asymptotically limited, for fast sources, to a value depending on the<br>radius of the source, scaled to the depth of the water column; as this<br>ratio increases, it becomes more difficult to flush the water out of<br>the source area during the generation process, resulting in greater<br>tsunami efficiency. Fortunately, this result should not affect<br>significantly the generation of tusnamis by mega-earthquakes.</p>

A High-Resolution Modeling Study of the 24 May 2002 Dryline Case during IHOP. Part I: Numerical Simulation and General Evolution of the Dryline and Convection

2006 ◽  
Vol 134 (1) ◽  
pp. 149-171 ◽  
Author(s):  
Ming Xue ◽  
William J. Martin
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
High Resolution ◽  
Companion Paper ◽  
Horizontal Resolution ◽  
Initial Condition ◽  
Moist Convection ◽  
Convective Initiation ◽  
Deep Moist Convection ◽  
Localized Forcing

Abstract Results from a high-resolution numerical simulation of the 24 May 2002 dryline convective initiation (CI) case are presented. The simulation uses a 400 km × 700 km domain with a 1-km horizontal resolution grid nested inside a 3-km domain and starts from an assimilated initial condition at 1800 UTC. Routine as well as special upper-air and surface observations collected during the International H2O Project (IHOP_2002) are assimilated into the initial condition. The initiation of convective storms at around 2015 UTC along a section of the dryline south of the Texas panhandle is correctly predicted, as is the noninitiation of convection at a cold-front–dryline intersection (triple point) located farther north. The timing and location of predicted CI are accurate to within 20 min and 25 km, respectively. The general evolution of the predicted convective line up to 6 h of model time also verifies well. Mesoscale convergence associated with the confluent flow around the dryline is shown to produce an upward moisture bulge, while surface heating and boundary layer mixing are responsible for the general deepening of the boundary layer. These processes produce favorable conditions for convection but the actual triggering of deep moist convection at specific locations along the dryline depends on localized forcing. Interaction of the primary dryline convergence boundary with horizontal convective rolls on its west side provides such localized forcing, while convective eddies on the immediate east side are suppressed by a downward mesoscale dryline circulation. A companion paper analyzes in detail the exact processes of convective initiation along this dryline.

scholarly journals The simulation of the flow through the porous media and diffusible barriers

2018 ◽  
Vol 180 ◽  
pp. 02052
Author(s):  
Martin Kyncl ◽  
Jaroslav Pelant
Keyword(s):  
Numerical Simulation ◽  
Porous Media ◽  
Fluid Flow ◽  
Compressible Fluid ◽  
Gas Flow ◽  
Initial Condition ◽  
Computational Results ◽  
Viscous Compressible Fluid ◽  
Compressible Fluid Flow ◽  
Flow Through

Here we work with the RANS equations describing the non-stationary viscous compressible fluid flow. We focus on the numerical simulation of the flow through the porous media, characterized by the loss of momentum. Further we simulate the flow through the set of diffusible barriers. Here we analyze the modification of the Riemann problem with one-side initial condition, complemented with the Darcy’s law and added inertial loss. We show the computational results obtained with the own-developed code for the solution of the compressible gas flow.

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