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Conference Papers Year : 2018

Boundary condition influence on instabilities in a low Reynolds free surface rotating flow

Abstract

The study of a rotating flow in one its most simple configuration (fixed cylindrical cavity, rotating bottom disk, free top surface) reveals a much more complicated physic than expected. While we tried to validate our experimental setup with both publica- tion 1 and numerical result, we were able to obtain the right unstable modes, but at much lower Reynolds. After several investigation on possibles issue in our experience, we finally suspected free condition surface to deeply influence both base flow and instabilities. We first used a condition introduced in 2, that we call “Frozen condition”, and that consists in setting the surface radial velocity to 0. But if this condition lowered the critical Reynolds, Stability analysis was no more able to predict the right mode. So we built a new top boundary condition as an α weighted sum of free and frozen conditions. A search for critical Reynolds depending on α reveals a second unstable branch, with a lower critical Reynolds, and better visualization agreement 1(c) with instabil- ities that are experimentally observed 1(b).
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Dates and versions

hal-04410318 , version 1 (22-01-2024)

Identifiers

  • HAL Id : hal-04410318 , version 1

Cite

Antoine Faugaret, Laurent Martin Witkowski, Yohann Duguet, Yann Fraigneau. Boundary condition influence on instabilities in a low Reynolds free surface rotating flow. 12th European Fluid Mechanics Conference, Sep 2018, Vienna, Austria. ⟨hal-04410318⟩
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