A multiscale porous--resolved methodology for efficient simulation of heat and fluid transport in complex geometries, with application to electric power transformers

TL;DR

This paper introduces a multiscale simulation method combining porous-medium and fully resolved models to efficiently simulate heat and fluid flow in complex geometries like power transformers, reducing computational costs while maintaining accuracy.

Contribution

The paper presents a novel multiscale simulation framework that couples porous-medium and detailed models for efficient analysis of complex heat and fluid transport problems.

Findings

Significant reduction in computational cost compared to full-resolution simulations.

Validation against analytical solutions and full models confirms accuracy.

Effective application to oil flow and heat transfer in power transformers.

Abstract

The numerical simulation of fluid flow through a complex geometry with heat transfer is of strong interest for many applications, such as oil-filled power transformers. A fundamental challenge here is that high resolution is necessary to resolve the fluid flow phenomena, but this makes simulation of the full geometry very expensive in terms of computational power. In this work, we develop a simulation methodology that combines a porous-medium approach for simulating some regions of the domain, coupled with fully resolved simulations in those regions which are deemed most interesting to study in detail. As one does not resolve flow features like thermal boundary layers in the regions modeled with the porous approach, the resolution in these parts can be orders of magnitude coarser. This multiscale approach is validated against the use of fully resolved simulations in the whole domain, as well as against analytical solutions to the extended Graetz problem. We then apply the approach to the study of oil flow and heat transfer in large electric power transformers and demonstrate a significant reduction in computational cost compared to a fully resolved approach.