Simulation of pure sedimentation of raindrops using quadrature method of moments

The quadrature method of moments (QMOM) is used for simulation of pure sedimentation of raindrops in a one-dimensional rainshaft. The moments have been calculated in three ways, based either on droplet diameter using two and three nodes or on droplet volume using two nodes. The method gives useful information on the range of sizes and also on spatial segregation of the droplets. The results show that all three methods give useful information about the transport processes involved and compare satisfactorily with the spectral (bin) method although use of diameter as internal coordinate is preferable from the viewpoint of quantitative agreement.

► Raindrop sedimentation simulated using QMOM in terms of volume and diameter. ► Two and three nodes used for diameter-based and two nodes for volume-based QMOM. ► Essential transport phenomena well captured by all QMOM simulations. ► Diameter-based QMOM with 3 nodes in best agreement with spectral solution.