An adaptive pathline-based particle tracking algorithm for the Eulerian-Lagrangian method

The accuracy in determining the Lagrangian concentration in the Eulerian-La grangian method depends on both the particle tracking algorithm and concent ration interpolation. In most existing particle tracking algorithms, accura te tracking cannot be achieved, particularly in a complicated unsteady flow . Also mechanisms for error estimation and accuracy control are not availab le. A new algorithm is developed by refining the process of particle tracki ng, making use of a series of available travel time increments (ATTIs). The ATTIs are selected on the basis of tracking accuracy and efficiency. These are controlled by practical indices related to the rate of particle veloci ty variation (magnitude and direction). The particle velocity is determined by bilinear interpolation in space and time. The proposed algorithm combin es an inter-element refinement; consistent with the piecewise interpolation of velocity. and an in-element pathline-based refinement. No mesh refineme nt is needed. Numerical simulations have been used to demonstrate the accur acy of the proposed algorithm. A comparison between the results obtained by using the proposed algorithm and by some existing techniques shows that th e new algorithm can provide an accurate and efficient particle tracking, es pecially in a complicated unsteady heterogeneous flow. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.