This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The present paper proposes a coupled 3D multi-physics model and presents the results of its
transient simulation, for a RF MEMS capacitive switch of bridge-type. The fluid structure interaction (FSI)
simulation sustains time-varying viscous damping and modified time response of the bridge deflection
compared to the actuation modulation above closing of the switch. Complex 3D geometries of the bridge
were rarely taken into account in viscous damping assessment much less in the simulation of the full flow
around the bridge of the switch. The final goal of the paper is to obtain the dependency of an equivalent
damping coefficient with respect to time, to be used in subsequent reduced order models for the switch, that
include the aerodynamic behaviour of the switch
