High-resolution numerical simulations of boundary layer flows in support of the METCRAX field program

We will describe both the numerical model we employ for high-resolution numerical simulations and its application to several examples of airflow in, over, and around the Arizona Meteor Crater performed in support of measurements made during the METCRAX experiment. The model is a spectral element (SE) code that permits descriptions of flows over terrain of arbitrary complexity, application of high spatial resolution in those portions of the computational domains where these needs are the greatest, and a variety of boundary conditions.

Simulations employing uniform stratification, constant and oscillatory boundary layer velocities, an azimuthally symmetric crater geometry, and laminar and turbulent boundary layers are employed to demonstrate simple flow responses within the crater and in the external boundary layer. The most notable responses are 1) small-scale internal waves excited by the topography of the crater lip that depend strongly on boundary layer flow velocities, 2) seiches that are excited with varying vertical structure, depending on the period of the forcing oscillation, and 3) fluid exchanges between the crater and the exterior flow. We believe the latter process, in particular, may significantly augment the rate of erosion of stable stratification in the crater expected from radiation or dynamical mixing within the crater or at the top of the crater cold pool.