Rarefied gas flows through meshes and implications for atmospheric measurements

Meshes are commonly used as part of instruments for in situ atmospheric mea surements. This study analyses the aerodynamic effect of meshes by means of wind tunnel experiments and numerical simulations. Based on the Direct Sim ulation Monte Carlo method, a simple mesh parameterisation is described and applied to a number of representative flow conditions. For open meshes fre ely exposed to the flow, substantial compression effects are found both ups tream and downstream of the mesh. Meshes attached to close instrument struc tures, on the other hand, cause only minor how disturbances. In an accompan ying paper, the approach developed here is applied to the quantitative anal ysis of rocket-borne density measurements in the middle atmosphere.