Development of a modal sub-structuring method : application to thermal simulations of LNG carriers

Abstract

In the context of simulations of coupled thermal enclosures, we present here a sub-structuring technique adapted to a reduced modal formulation. This technique consists in splitting the geometry into different zones. A modal model is then applied to each zone, and the coupling of the resulting models is performed via a thermal contact resistance. This technique allows the consideration of physical thermal resistances between different components of the geometry, but also the making of fictitious cuts within a continuous domain, when its large size makes it difficult to obtain the global reduced model. Applied to the simulation of a component of a LNG carrier, the use of a sub-structured model with 200 modes allows almost immediate resolution (around 1 second) for a maximum difference near 1 K and an average difference of the order of 0.2 K with respect to a conventional Lagrange finite elements model of shell type, which requires 40 times longer calculation.