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Numerical Experiments Using Modified POM WAD with Computing Time Saving Technique (계산시간절약기법이 적용된 수정 POM WAD의 수치실험)

  • Park, Il Heum;Choi, Heung Bae
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.21 no.1
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    • pp.72-82
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    • 2015
  • In order to effectively and economically apply the previous POM(Princeton Ocean Model) WAD(Wetting And Drying) to the coastal area, the POM WAD was modified such as the water elevation input of tidal harmonics in the open boundaries was included and a CTS(Computing Time Saving) technique was introduced to the model. The modified model was tested to the standing waves in the rectangular bay and the hydraulic experiments for the flow and heat diffusion in the 3D basin. The numerical results showed a good agreement with the analytical solutions of the standing waves and the observed values by the hydraulic experiments, respectively. And also when the modified model with the CTS technique was applied to Gwangyang Bay of Korea, the computing time was decreased by as much as 39.4%.

NONPOTENTIAL PARAMETERS OF SOLAR ACTIVE REGION AR 5747

  • MOON Y.-J.;YUN H. S.;CHOE GWANGSON;PARK Y. D.;MICKEY D. L.
    • Journal of The Korean Astronomical Society
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    • v.33 no.1
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    • pp.47-55
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    • 2000
  • Nonpotential characteristics of magnetic fields in AR 5747 are examined using Mees Solar Observatory magnetograms taken on Oct. 20, 1989 to Oct. 22, 1989. The active region showed such violent flaring activities during the observational span that strong X-ray flares took place including a 2B/X3 flare. The magnetogram data were obtained by the Haleakala Stokes Polarimeter which provides simultaneous Stokes profiles of the Fe I doublet 6301.5 and 6302.5. A nonlinear least square method was adopted to derive the magnetic field vectors from the observed Stokes profiles and a multi-step ambiguity solution method was employed to resolve the $180^{\circ}$ ambiguity. From the ambiguity-resolved vector magnetograms, we have derived a set of physical quantities characterizing the field configuration, which are magnetic flux, vertical current density, magnetic shear angle, angular shear, magnetic free energy density, a measure of magnetic field discontinuity MAD and linear force-free coefficient. Our results show that (1) magnetic nonpotentiality is concentrated near the inversion line in the flaring sites, (2) all the physical parameters decreased with time, which may imply that the active region was in a relaxation stage of its evolution, (3) 2-D MAD has similar patterns with other nonpotential parameters, demonstrating that it can be utilized as an useful parameter of flare producing active region, and (4) the linear force-free coefficient could be a evolutionary indicator with a merit as a global nonpotential parameter.

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Density Anomalies of Generalized van der Waals Fluid (일반화된 van der Waals 유체의 밀도 비이상성)

  • Yeo, Sang-Do;Debenedetti, Pablo G.
    • Applied Chemistry for Engineering
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    • v.7 no.4
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    • pp.809-812
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    • 1996
  • Generalized van der Waals equation of state combined with the core-softening theory and temperature dependent repulsive and attractive terms exhibit the anomalous thermal expansion, i.e. density anomaly. Density maxima occur at both positive and negative pressure when the hard-core diameter decreases with increasing temperature, $db_r/dT_r<0$, and at negative pressure when the repulsive force increases with increasing temperature, $da_r/dT_r>0$.

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Ocean Outfall Modelling with the Particle Tracking Method (입자추적법을 이용한 해양방류구 모델링)

  • Jung, Yun-Chul
    • Journal of Navigation and Port Research
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    • v.26 no.5
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    • pp.563-569
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    • 2002
  • To overcome the weaknesses of conventional finite difference model in pollutant dispersion modelling, the particle tracking method is used. In this study, a three dimensional particle tracking model which can be used in Princeton Ocean Model was developed and verified through the various numerical tests. Usability of the model was also confirmed through the ocean outfall modelling in Tampa Bay, Florida. As it is expected, random walk model showed the less dispersion in a range compared to the conventional finite difference model and its reason is estimated due to an error from numerical diffusion which the conventional model holds. This newly developed model is expected to be used in various ocean dispersion modelling.