An algorithm for tracking fluid particles in a spectral simulation of turbulent channel flow

Abstract

The ability to follow individual fluid particles dispersing in a turbulent flow and to collect turbulence information along their trajectories is of key importance in many problems of practical and theoretical significance. With the availability of a direct numerical simulation of turbulence such information can be extracted directly from first principles without resorting to questionable assumptions. In this paper an algorithm for tracking fluid particles in a direct numerical simulation of turbulent channel flow is developed and tested. Fluid particle velocities are computed with an interpolation scheme that employs Lagrange polynomials of order 6 in the homogeneous directions of the channel and Chebyshev polynomials in the inhomogeneous normal direction. Errors in computed particle velocities and trajectories are assessed and it is shown that accurate single-particle Lagrangian statistics can be extracted both in the center and in the wall region of the channel.