Multiphase wall-bounded turbulence

Dennis Bakhuis

Research output: ThesisPhD Thesis - Research UT, graduation UTAcademic

128 Downloads (Pure)

Abstract

In many geophysical situations and in all industrial applications, turbulent flows are wall-bounded. Many of these flows are multi-phase, i.e. flows consisting of one or multiple inclusions. The current understanding of these flows is still limited and this makes it important to study them. In this thesis we study these wall-bounded multi-phase flows in two canonical systems: Taylor-Couette flow (TC) and Rayleigh-Bénard convection (RBC). In this work we used spherical and cylindrical particles to investigate if we have reduced skin friction similar to bubbly drag reduction. The global torque measurements showed that these particles barely alter the drag, even at very large particle volume fractions. Surprisingly, we found a preferential alignment for the cylindrical particles with respect to the inner cylinder wall. Using oil and water we are able to create deformable inclusions. Increasing the oil volume fraction over a critical point results in phase inversion with water droplets in oil. In this regime we found drag reduction due to the large water droplets in the flow. This is confirmed with in-situ microscopic imaging. In the last two chapters of this thesis we study the effect of non-homogeneous boundaries in both TC and RBC. Using bands of sandgrain roughness we were able to control the secondary flows in TC. This means that for example roughness like barnacles on the hull of a ship can induce secondary flows that push air bubbles away and thereby, reducing the drag reducing effect.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Twente
Supervisors/Advisors
  • Sun, Chao , Supervisor
  • Lohse, Detlef , Supervisor
  • Huisman, Sander Gerard, Co-Supervisor
Thesis sponsors
Award date31 Jan 2019
Place of PublicationEnschede
Publisher
Electronic ISBNs978-90-365-4679-9
DOIs
Publication statusPublished - 31 Jan 2019

Fingerprint

Couette flow
turbulence
drag reduction
secondary flow
multiphase flow
theses
oils
drag
convection
roughness
inclusions
water
skin friction
ships
turbulent flow
torque
critical point
bubbles
alignment
inversions

Keywords

  • Turbulence
  • multiphase and particle-laden flows
  • Rough surfaces
  • Taylor-Couette flow
  • Rayleigh-Bénard convection

Cite this

Bakhuis, D. (2019). Multiphase wall-bounded turbulence. Enschede: University of Twente. https://doi.org/10.3990/1.9789036546799
Bakhuis, Dennis . / Multiphase wall-bounded turbulence. Enschede : University of Twente, 2019. 145 p.
@phdthesis{89f0a22e2cab4b69bdf60de4db95b0df,
title = "Multiphase wall-bounded turbulence",
abstract = "In many geophysical situations and in all industrial applications, turbulent flows are wall-bounded. Many of these flows are multi-phase, i.e. flows consisting of one or multiple inclusions. The current understanding of these flows is still limited and this makes it important to study them. In this thesis we study these wall-bounded multi-phase flows in two canonical systems: Taylor-Couette flow (TC) and Rayleigh-B{\'e}nard convection (RBC). In this work we used spherical and cylindrical particles to investigate if we have reduced skin friction similar to bubbly drag reduction. The global torque measurements showed that these particles barely alter the drag, even at very large particle volume fractions. Surprisingly, we found a preferential alignment for the cylindrical particles with respect to the inner cylinder wall. Using oil and water we are able to create deformable inclusions. Increasing the oil volume fraction over a critical point results in phase inversion with water droplets in oil. In this regime we found drag reduction due to the large water droplets in the flow. This is confirmed with in-situ microscopic imaging. In the last two chapters of this thesis we study the effect of non-homogeneous boundaries in both TC and RBC. Using bands of sandgrain roughness we were able to control the secondary flows in TC. This means that for example roughness like barnacles on the hull of a ship can induce secondary flows that push air bubbles away and thereby, reducing the drag reducing effect.",
keywords = "Turbulence, multiphase and particle-laden flows, Rough surfaces, Taylor-Couette flow, Rayleigh-B{\'e}nard convection",
author = "Dennis Bakhuis",
year = "2019",
month = "1",
day = "31",
doi = "10.3990/1.9789036546799",
language = "English",
publisher = "University of Twente",
address = "Netherlands",
school = "University of Twente",

}

Bakhuis, D 2019, 'Multiphase wall-bounded turbulence', Doctor of Philosophy, University of Twente, Enschede. https://doi.org/10.3990/1.9789036546799

Multiphase wall-bounded turbulence. / Bakhuis, Dennis .

Enschede : University of Twente, 2019. 145 p.

Research output: ThesisPhD Thesis - Research UT, graduation UTAcademic

TY - THES

T1 - Multiphase wall-bounded turbulence

AU - Bakhuis, Dennis

PY - 2019/1/31

Y1 - 2019/1/31

N2 - In many geophysical situations and in all industrial applications, turbulent flows are wall-bounded. Many of these flows are multi-phase, i.e. flows consisting of one or multiple inclusions. The current understanding of these flows is still limited and this makes it important to study them. In this thesis we study these wall-bounded multi-phase flows in two canonical systems: Taylor-Couette flow (TC) and Rayleigh-Bénard convection (RBC). In this work we used spherical and cylindrical particles to investigate if we have reduced skin friction similar to bubbly drag reduction. The global torque measurements showed that these particles barely alter the drag, even at very large particle volume fractions. Surprisingly, we found a preferential alignment for the cylindrical particles with respect to the inner cylinder wall. Using oil and water we are able to create deformable inclusions. Increasing the oil volume fraction over a critical point results in phase inversion with water droplets in oil. In this regime we found drag reduction due to the large water droplets in the flow. This is confirmed with in-situ microscopic imaging. In the last two chapters of this thesis we study the effect of non-homogeneous boundaries in both TC and RBC. Using bands of sandgrain roughness we were able to control the secondary flows in TC. This means that for example roughness like barnacles on the hull of a ship can induce secondary flows that push air bubbles away and thereby, reducing the drag reducing effect.

AB - In many geophysical situations and in all industrial applications, turbulent flows are wall-bounded. Many of these flows are multi-phase, i.e. flows consisting of one or multiple inclusions. The current understanding of these flows is still limited and this makes it important to study them. In this thesis we study these wall-bounded multi-phase flows in two canonical systems: Taylor-Couette flow (TC) and Rayleigh-Bénard convection (RBC). In this work we used spherical and cylindrical particles to investigate if we have reduced skin friction similar to bubbly drag reduction. The global torque measurements showed that these particles barely alter the drag, even at very large particle volume fractions. Surprisingly, we found a preferential alignment for the cylindrical particles with respect to the inner cylinder wall. Using oil and water we are able to create deformable inclusions. Increasing the oil volume fraction over a critical point results in phase inversion with water droplets in oil. In this regime we found drag reduction due to the large water droplets in the flow. This is confirmed with in-situ microscopic imaging. In the last two chapters of this thesis we study the effect of non-homogeneous boundaries in both TC and RBC. Using bands of sandgrain roughness we were able to control the secondary flows in TC. This means that for example roughness like barnacles on the hull of a ship can induce secondary flows that push air bubbles away and thereby, reducing the drag reducing effect.

KW - Turbulence

KW - multiphase and particle-laden flows

KW - Rough surfaces

KW - Taylor-Couette flow

KW - Rayleigh-Bénard convection

U2 - 10.3990/1.9789036546799

DO - 10.3990/1.9789036546799

M3 - PhD Thesis - Research UT, graduation UT

PB - University of Twente

CY - Enschede

ER -

Bakhuis D. Multiphase wall-bounded turbulence. Enschede: University of Twente, 2019. 145 p. https://doi.org/10.3990/1.9789036546799