초록: We shall discuss in this talk the evolution of bubbles of gas inside an inviscid or viscous liquid. The goal is to identify simpler models than the full two-fluid model with free liquid/gas interfaces. A typical example of simplification is to neglect the deviation from sphericity of the bubbles. We will first present a variational approach to derive reduced models, and then discuss  their well-posedness. All the talk is based on joint work with Cosmin Burtea.