Hybrid asymptotic-numerical modeling of thin layers for dynamic thermal analysis of structures

Abstract

Purpose -The purpose of this paper is to propose a computational model for thin layers, for problems of linear time-dependent heat conduction. The thin layer is replaced by a zero-thickness interface. The advantage of the new model is that it saves the need to construct and use a fine mesh inside the layer and in regions adjacent to it, and thus leads to a reduction in the computational effort associated with implicit or explicit finite element schemes. Design/methodology/approach -Special asymptotic models have been proposed for linear heat transfer and linear elasticity, to handle thin layers. In these models the thin layer is replaced by an interface with zero thickness, and specific jump conditions are imposed on this interface in order to represent the special effect of the layer. One such asymptotic interface model is the first-order Bövik-Benveniste model. In a paper by Sussmann et al., this model was incorporated in a FE formulation for linear steady-state heat conduction problems, and was shown to yield an accurate and efficient computational scheme. Here, this work is extended to the time-dependent case. Findings -As shown here, and demonstrated by numerical examples, the new model offers a costeffective way of handling thin layers in linear time-dependent heat conduction problems. The hybrid asymptotic-FE scheme can be used with either implicit or explicit time stepping. Since the formulation can easily be symmetrized by one of several techniques, the lack of self-adjointness of the original formulation does not hinder an accurate and efficient solution. Originality/value -Most of the literature on asymptotic models for thin layers, replacing the layer by an interface, is analytic in nature. The proposed model is presented in a computational context, fitting naturally into a finite element framework, with both implicit and explicit time stepping, while saving the need for expensive mesh construction inside the layer and in its vicinity.

An asymptotic-numerical comparative study for axisymmetric free surface liquid jet near and far from exit at high Reynolds number

“…Asymptotic-numerical methods have been widely used in flow and heat transfer problems (Störtkuhl et al, 1994;Grundmann et al, 1996;Tuval et al, 2016) due to their computational efficiency. More importantly, the asymptotic approach provides a deeper insight into the flow structure and the rich dynamics near the singularity.…”

“…In contrast, an asymptotic approach lends itself efficiently as a viable alternative as the singularity is avoided altogether because of the boundary layer or similarity character of the flow near the free surface. HFF 30,10 Asymptotic-numerical methods have been widely used in flow and heat transfer problems (Störtkuhl et al, 1994;Grundmann et al, 1996;Tuval et al, 2016) due to their computational efficiency. More importantly, the asymptotic approach provides a deeper insight into the flow structure and the rich dynamics near the singularity.…”