• Title/Summary/Keyword: calibration of unsteady friction model

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Application of Levenberg Marquardt Method for Calibration of Unsteady Friction Model for a Pipeline System (관수로 부정류 마찰항 보정을 위한 Levenberg Marquardt 방법의 적용연구)

  • Park, Jo Eun;Kim, Sang Hyun
    • Journal of Korea Water Resources Association
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    • v.46 no.4
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    • pp.389-400
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    • 2013
  • In this study, a conventional pipeline unsteady friction model has been integrated into Levenberg Marquardt method to calibrate friction coefficient in a pipeline system. The method of characteristics has been employed as the modeling platform for the frequency dependant model of unsteady friction. In order to obtain Hessian and Jacobian matrix for optimization, the direct differentiation of pressure to friction factor was calculated and sensitivities to friction for heads and discharges were formulated for implementation to the integration constant in the characteristic method. Using a hypothetical simple pipeline system, time series of pressure, introduced by a sudden valve closure, were obtained for various Reynolds numbers. Convergency in fiction factors were evaluated both in steady and unsteady friction models. The comparison of calibration performance between the proposed method and genetic algorithm indicates that faster and stabler behaviour of Levenberg Marquardt method than those of evolutionary calibration.