Reverse simulation of sinking EDM applicable to large curvatures

2012 ◽  
Vol 36 (2) ◽  
pp. 238-243 ◽  
Author(s):  
Masanori Kunieda ◽  
Yuki Kaneko ◽  
Wataru Natsu
Keyword(s):  
Reverse Simulation

scholarly journals Study on the Dependence of Reverse Simulation for Identifying a Pollutant Source on Grid Resolution and Filter Width in Cavity Flow

2012 ◽  
Vol 2012 ◽  
pp. 1-16 ◽  
Author(s):  
Satoshi Abe ◽  
Shinsuke Kato ◽  
Fujihiro Hamba ◽  
Daisuke Kitazawa
Keyword(s):  
Cavity Flow ◽  
Grid Resolution ◽  
Hazardous Substance ◽  
Simulation Accuracy ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Filter Width ◽  
Pollutant Source ◽  
Reverse Simulation ◽  
Negative Diffusion

When a hazardous substance is diffused, it is necessary to identify the pollutant source and respond immediately. However, there are many cases in which damage is caused without a clear understanding of where the pollutant source is located. There are three groups of identifying pollutant source information (Liu and Zhai, 2007): the probability method, forward method, and backward method. In our previous study, we proposed reverse simulation, which is categorized as a backward method (Abe and Kato, 2011). Numerical instability by negative diffusion is a principal problem in the backward method. In order to improve the problem, we applied a low-pass filter operation to the concentration flux in the RANS analysis. The simulation secured the numerical stability. However, reverse simulation accuracy is expected to depend on the grid resolution and filter width. In this paper, we introduce reverse simulation results in cavity flow. In particular, we survey the dependence of reverse simulation accuracy on the grid resolution and filter width. Moreover, we discuss the dependence of reverse simulation on the grid resolution and filter width with a one-dimensional diffusion equation. As a result, we found that the simulated negative diffusion varies greatly among the grid resolution and filter width.

scholarly journals NIMG-29. TUMOR RECURRENCE IN AREAS OF LOWER TTFIELDS INTENSITY: A REVERSE SIMULATION CASE STUDY

2016 ◽  
Vol 18 (suppl_6) ◽  
pp. vi130-vi130
Author(s):  
James Battiste ◽  
Michael Sughrue ◽  
Ariel Naveh ◽  
Aafia Chaudhry
Keyword(s):  
Tumor Recurrence ◽  
Reverse Simulation

Reverse Simulation of Die-Sinking EDM

CIRP Annals ◽  
1999 ◽  
Vol 48 (1) ◽  
pp. 115-118 ◽  
Author(s):  
Masanori Kunieda ◽  
Wataru Kowaguchi ◽  
Takashi Takita
Keyword(s):  
Reverse Simulation

A New Forging Preform Design Approach Using Reverse Simulation

CIRP Annals ◽  
1998 ◽  
Vol 47 (1) ◽  
pp. 193-196 ◽  
Author(s):  
C.C. Chang ◽  
A.N. Bramley
Keyword(s):  
Design Approach ◽  
Preform Design ◽  
Reverse Simulation

Reverse Simulation for Specifying the Source of Pollutants in Waters

2011 ◽  
Author(s):  
Daisuke Kitazawa ◽  
Satoshi Abe ◽  
Fujihiro Hamba ◽  
Shinsuke Kato
Keyword(s):  
Numerical Simulation ◽  
Point Source ◽  
Trajectory Analysis ◽  
Water Current ◽  
Frequency Variation ◽  
Gaussian Filter ◽  
Forward Simulation ◽  
Filter Width ◽  
Advection Diffusion Equation ◽  
Reverse Simulation

Reverse simulation was carried out to specify the point source of pollutants in closed waters. If pollutants flow out into waters, their source must be specified as soon as possible to take a quick measure against the pollution problem. Actually, a wide variety of pollutants have been released into the aquatic environment, some with catastrophic consequences for aquatic life or man. Numerical simulation is one of the powerful tools to specify the point source of pollutants. An inverse trajectory analysis has been used in the case when an advective process of pollutants is dominant. However, the inverse trajectory analysis does not take the diffusion of pollutants into account. Several analytical techniques are applicable only to simple current fields. The present study proposes reverse simulation to specify the point source of pollutants. The basic equation of the reverse simulation is given by changing the positive time derivative term of the advection-diffusion equation of pollutants into a negative term. First, numerical simulation was executed in a forward direction. The results of water current velocities were preserved for the following reverse simulation. Assuming that the pollutants are subject to the surrounding water current and turbulence like a tracer, the advection and diffusion processes of the tracer could be solved for obtaining the initial condition of reverse simulation, and for the following comparison with the results of reverse simulation. The predicted result of water current velocities in the forward simulation was given to calculate the advection-diffusion equation of the tracer. One of the major problems of reverse simulation is the instability of numerical simulation. A Gaussian filter was used for the spatial distribution of the tracer or of the flux of the tracer to eliminate the numerical instability, and the optimum filter width was discussed. As a result, the instability of reverse simulation was suppressed by applying the Gaussian filter for the spatial distribution of the tracer. However, the concentration of the tracer was not condensed in comparison with the result of the tracer in the forward simulation. When the Gaussian filter was used for the special distribution of the flux of the tracer, the accuracy of the prediction of the point source was improved. This is because the high frequency variation was suppressed, keeping the low frequency variation. The concentration of the tracer was more condensed with smaller filter width in both cases. The future studies are to determine the filter width adequately and to modify the difference equation of the Gaussian filter.

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