         SALVATORE NIGRO, LEONARDO PAGNOTTA, MARIA F. PANTANO Department of Mechanical Engineering University of Calabria Ponte P. Bucci, 44C, 87036 Rende ITALY mf.pantano@unical.it , http://www.meccanica.unical.it  In this paper, analytical and numerical methods for simulating squeeze7film air damping affecting suspended and perforated movable micro7surfaces are analyzed. Numerical solutions are obtained by full 37D Navier7Stokes numerical analysis, carried out by a commercial finite element code, COMSOL Multiphysics, and are compared with those obtained using different analytical models proposed in literature. The numerical and analytical solutions are also compared with published experimental measurements. Investigated cases are experimentally studied rectangular plates, which differ from one another for the size, the number and the position of perforations.   Squeeze7film damping, MEMS, Navier7Stokes equation, FEA, COMSOL Multiphysics   The aim of the mechanical design of inertial sensors, like accelerometers, is to get the desired dynamic behavior (i. e. frequency response and quality factor). This achievement strongly depends on damping phenomena, which affect the movement of movable elements, like the seismic mass. At micro7scale, the main damping source is the so7 called   . It is related to the presence of a thin film of fluid (usually air) confined between two walls in relative normal movement, and becomes significant especially when the thickness of the air layer is at least one third of the wall size. Since such a geometry is very common in MEMS (Micro Electro7Mechanical Systems) devices, for example in plate7shaped or comb7drive accelerometers, this phenomenon has attracted great interest with time. The squeeze7film air damping can be explained by considering what happens into the air gap when one of the plates moves. In particular, when one of the two walls moves normally with respect to the other one, the fluid is sucked into/pulled out of the gap, and a significant pressure field arises into the channel. This phenomenon causes the generation of a resistive force on the movable plate. When the ambient pressure is high (i. e. atmospheric pressure), the motion of the fluid caused by the relative movement of the two surfaces can be modeled through the Navier7Stokes equation [1]. In most applications, it is possible to further simplify the problem (if non7steady effects, fluid inertia and thermal gradient are negligible) and to use the simpler Reynolds equation [2]. Such an equation can be analytically solved for simple geometries, like rectangular, circular and annular plates [3]. On the other hand, when the movable plate is perforated, the previous equation does not apply. For this reason, during the last two decades new and appropriate models, based on the classical Navier7 Stokes and Reynolds approaches, have been introduced. Unfortunately, these analytical models can be adopted for a restricted number of simple regular geometries, while the structures of MEMS devices are generally complex and irregular. In such cases, for accurately modeling, simulating and analyzing squeeze film damping a numerical method, as the finite element method (FEM), should be used. The present work investigates on this perspective. In the paper, solutions, obtained for some referenced cases by a commercial finite element software, COMSOL Multiphysics, have been compared with those obtained using five different analytical models proposed in literature and the experimental results provided by other authors.        Throughout the years, many analytical models have NEW ASPECTS of FLUID MECHANICS, HEAT TRANSFER and ENVIRONMENT ISSN: 1792-4596 314 ISBN: 978-960-474-215-8