Use of natural instabilities for generation of streamwise vortices in a laminar channel flow

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalNot applicablepeer-review

4 Scopus Citations
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Author(s)

Detail(s)

Original languageEnglish
Pages (from-to)233-250
Journal / PublicationTheoretical and Computational Fluid Dynamics
Volume31
Issue number3
Online published19 Dec 2016
Publication statusPublished - Jun 2017
Externally publishedYes

Abstract

An analysis of pressure-gradient-driven flows in channels with walls modified by transverse ribs has been carried out. The ribs have been introduced intentionally in order to generate streamwise vortices through centrifugally driven instabilities. The cost of their introduction, i.e. the additional pressure losses, have been determined. Linear stability theory has been used to determine conditions required for the formation of the vortices. It has been demonstrated that there exists a finite range of rib wave numbers capable of creating vortices. Within this range, there exists an optimal wave number which results in the minimum critical Reynolds number for the specified rib amplitude. The optimal wave numbers marginally depend on the rib positions and amplitudes. As the formation of the vortices can be interfered with by viscosity-driven instabilities, the critical conditions for the onset of such instabilities have also been determined. The rib geometries which result in the vortex formation with the smallest drag penalty and without interference from the viscosity-driven instabilities have been identified.

Research Area(s)

  • Laminar channel flow, Mixing enhancement, Transverse grooves, Viscosity-driven instability, Vortex instability