The principal modelling package used by Xi Engineering Consultants is COMSOL Multiphysics and Xi are recognised internationally as COMSOL Certified Consultants. COMSOL provides a true Multiphysics environment providing Xi with the ability to fully couple different physical phenomena to simulated complex behaviour. Common multiphysics models produced by Xi include acoustic-structural dynamics, acoustic-MEMS, structural dynamics-fluid flow, electrostatic-structural-acoustic and electromagnetic-structural dynamics.
An example of Xi applying multiphysics simulation involved a project where they modelled electrostatic headphones. Electrostatic speakers work by driving a changed elastic membrane between two parallel conductive wire meshes to which an AC signal is applied. The forces on the membrane vary the AC signal level and with distance to the wire mesh which in turn is dependent on the elasticity of the membrane and internal stresses. The dynamics are further complicated by the external load of the air on the membrane and visco-thermal losses. Solving such interrelated physics requires a multiphysics approach, which couples structural dynamics, electrostatics and acoustics.