Review on open-problems of spin-up flow of an incompressible fluid

We conduct experiments in a circular pipe with rotating Hagen–Poiseuille flow (RHPF) to which we apply spin-down or impulsive spin-down to rest, in order to analyse the threshold between convective and absolute instabilities through flow visualisations in the inlet region of the pipe. For a constant value of the Reynolds number, $Re$, the finite-amplitude wave packets generated by the arbitrary perturbation that results by reducing the swirl parameter, propagate upstream or downstream depending on the initial value of the swirl parameter, $L_{0}$. In fact, the main characteristic of the flow is that the velocity front of these wave packets changes from negative to positive when absolutely unstable modes are present in the initial state. The experimental results show that spin-down becomes a precise, reliable procedure to detect the onset of absolute instabilities. In addition, we give evidence of a gradual transition for Reynolds numbers ranging from 300 to 500 where a mode shift from $n=-1$ to $n=-2$ appears in the absolutely unstable region.

show abstract

Spin-down in rotating Hagen–Poiseuille flow: a simple criterion to detect the onset of absolute instabilities

Miranda-Barea

Fabrellas-García

Parras

et al. 2016

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

Numerical investigation of the flow inside a precession-driven cylindrical cavity with additional baffles using an immersed boundary method

2022

View full text Add to dashboard Cite

In this paper we present a numerical approach to solve the Navier-Stokes equations for arbitrary vessel geometries by combining a Fourier-Spectral method with a direct forcing Immersed Boundary method which allows to consider solid-fluid interactions. The approach is applied to a paradigmatic setup motivated by the precession dynamo experiment currently under construction at Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The experiment consists of a fluid filled cylinder rotating about 2 axes which induces a precession driven flow inside the cavity. The cylinder is also equipped with baffles at the end caps with adjustable penetration depth to impact the flow. The numerical details as well as simulation results for the spin-up and precession driven flow in a circular cylinder with additional baffles are presented. The results provide a first confirmation that the use of such baffles in the precession dynamo experiment is a useful way of influencing the flow, allowing more efficient driving without changing the known flow structure too much.

show abstract

Spin-Up from Rest of a Liquid Metal with Deformable Free Surface in a Cylinder under the Influence of a Uniform Axial Magnetic Field

Tagawa

Song

2021

Fluids

View full text Add to dashboard Cite

Spin-up from rest of a liquid metal having deformable free surface in the presence of a uniform axial magnetic field is numerically studied. Both liquid and gas phases in a vertically mounted cylinder are assumed to be an incompressible, immiscible, Newtonian fluid. Since the viscous dissipation and the Joule heating are neglected, thermal convection due to buoyancy and thermocapillary effects is not taken into account. The effects of Ekman number and Hartmann number were computed with fixing the Froude number of 1.5, the density ratio of 800, and the viscosity ratio of 50. The evolutions of the free surface, three-component velocity field, and electric current density are portrayed using the level-set method and HSMAC method. When a uniform axial magnetic field is imposed, the azimuthal momentum is transferred from the rotating bottom wall to the core region directly through the Hartmann layer. This is the most striking difference from spin-up of the nonmagnetic case.

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

customersupport@researchsolutions.com

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Review on open-problems of spin-up flow of an incompressible fluid

Cited by 3 publications

References 34 publications

Spin-down in rotating Hagen–Poiseuille flow: a simple criterion to detect the onset of absolute instabilities

Spin-down in rotating Hagen–Poiseuille flow: a simple criterion to detect the onset of absolute instabilities

Numerical investigation of the flow inside a precession-driven cylindrical cavity with additional baffles using an immersed boundary method

Spin-Up from Rest of a Liquid Metal with Deformable Free Surface in a Cylinder under the Influence of a Uniform Axial Magnetic Field

Contact Info

Product

Resources

About