Heat-transfer enhancement by adaptive reorientation of flow fields

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Abstract

Scope is enhancement of scalar transport (heat, chemical species) in engineered flow systems by reorientations of a laminar base flow. Practical applications include mixing in inline heat exchangers by downstream reorientation of baffles, stirring in bio-reactors by cyclic repositioning of impellers, and subsurface chemicals distribution for in situ minerals mining by unsteady pumping schemes. Conventional reorientation schemes consist of a periodic reorientation (in space or time) of the flow designed to accomplish efficient fluid mixing. However, whether this approach indeed yields optimal scalar transport for significant diffusion and/or chemical reactions is unclear. The present study explores an alternative approach: adaptive reorientation of the flow by interval-wise selection of the reorientation that is predicted to yield optimal scalar transport for a future time horizon. Key enabler for fast predictions is a compact model based on the spectral decomposition of the scalar evolution in the base
flow. The adaptive reorientation scheme is investigated for a representative problem: enhanced heating of a cold fluid in a 2D circular domain by an unsteady flow driven by step-wise activation of moving boundary segments. This reveals that the adaptive reorientation scheme can substantially accelerate
the heating compared to conventional time-periodic reorientation designed for efficient mixing and thus demonstrates its potential for attaining optimal scalar transport in reoriented flows.
Original languageEnglish
Title of host publicationProceedings 5th Thermal and Fluids Engineering Conference (TFEC)
Publication statusAccepted/In press - 2020
Event5th Thermal and Fluids Engineering Conference (TFEC) - New Orleans, United States
Duration: 5 Apr 20208 Apr 2020

Conference

Conference5th Thermal and Fluids Engineering Conference (TFEC)
CountryUnited States
CityNew Orleans
Period5/04/208/04/20

Keywords

  • scalar transport
  • chaotic advection
  • thermal control

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