Modeling artifacts in the simulation of the sedimentation of raindrops with a Quadrature Method of Moments

The Quadrature Method of Moments (QMoM) is applied to a one-dimensional test case for sedimentation of raindrops. Comparison of the results with a reference spectral method exhibits discrepancies ("step patterns") that must be considered as modeling artifacts. As the QMoM has been demonstrated to be effective and accurate in various contexts, the origin of these artifacts is investigated and found to be related to the transport of the quadrature abscissas. Further test cases are considered to examine the influence of different initial conditions on the development of the modeling artifacts. The study shows that these artifacts are inherent to the application of QMoM in pure sedimentation context.