A new method to calculate unsteady particle kinematics and drag coefficient in a subsonic post-shock flow

Ankur D. Bordoloi, Liuyang Ding, Adam A. Martinez, Katherine Prestridge, Ronald Adrian

Research output: Contribution to journalArticle

2 Scopus citations


We introduce a new method (piecewise integrated dynamics equation fit, PIDEF) that uses the particle dynamics equation to determine unsteady kinematics and drag coefficient (C D) for a particle in subsonic post-shock flow. The uncertainty of this method is assessed based on simulated trajectories for both quasi-steady and unsteady flow conditions. Traditional piecewise polynomial fitting (PPF) shows high sensitivity to measurement error and the function used to describe C D, creating high levels of relative error (≫1) when applied to unsteady shock-accelerated flows. The PIDEF method provides reduced uncertainty in calculations of unsteady acceleration and drag coefficient for both quasi-steady and unsteady flows. This makes PIDEF a preferable method over PPF for complex flows where the temporal response of C D is unknown. We apply PIDEF to experimental measurements of particle trajectories from 8-pulse particle tracking and determine the effect of incident Mach number on relaxation kinematics and drag coefficient of micron-sized particles.

Original languageEnglish (US)
Article number074001
JournalMeasurement Science and Technology
Issue number7
Publication statusPublished - May 17 2018



  • kinematics measurement
  • particle tracking accelerometry
  • shock-particle interaction
  • unsteady drag

ASJC Scopus subject areas

  • Instrumentation
  • Engineering (miscellaneous)
  • Applied Mathematics

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