ABSTRACT

This chapter focuses on Lagrangian dispersion with large-eddy simulation (LES). LES was used first in micrometeorology by J. W. Deardorff. The growth in size, speed, and availability of supercomputers has since made LES more and more suitable to planetary boundary layer (PBL) applications. The PBL is the lowest layer of the atmosphere in which the direct effect of the earth’s surface on dynamical processes plays a relevant role, and it is also the environment in which almost all human and biological activities take place. The PBL can be considered as a continuous fluid characterized by a mixture of many subsidiary motions with different scales in space and time. The chapter examines the problem of relative dispersion in a neutrally stratified and celebrated Richardson’s law. The classical time-dependent approach in isolating Richardson’s law with the classical statistical technique has been inconclusive due to its strong dependency on initial conditions, which consequently does not permit an accurate estimate of the Richardson constant.