Imperial College London

DrJanetWong

Faculty of EngineeringDepartment of Mechanical Engineering

Senior Lecturer
 
 
 
//

Contact

 

+44 (0)20 7594 8991j.wong

 
 
//

Location

 

671City and Guilds BuildingSouth Kensington Campus

//

Summary

 

Publications

Citation

BibTex format

@article{Ponjavic:2015:10.1039/C5RA19245E,
author = {Ponjavic, A and Dench, J and Morgan, N and Wong, J},
doi = {10.1039/C5RA19245E},
journal = {RSC Advances},
pages = {99585--99593},
title = {In situ viscosity measurement of confined liquids},
url = {http://dx.doi.org/10.1039/C5RA19245E},
volume = {5},
year = {2015}
}

RIS format (EndNote, RefMan)

TY  - JOUR
AB - The viscosity of liquids governs crucial physical and engineering phenomena, ranging from diffusion and transport processesof nutrients and chemicals, to the generation of friction and the physics of damping. Engineering fluids frequently experiencelocal conditions that change their bulk rheological properties. While viscosity data can easily be acquired using conventionalrheometers, the results are not always applicable to fluids under engineering conditions. This is particularly the case forfluids being sheared at high pressure under severe confinement, which experience very high shear stresses and often showextensive shear thinning. There is a lack of suitable methods for measuring fluid viscosity under such conditions. This workdescribes a novel in-situ viscosity measurement technique to fill this gap. It involves the quantification of the fluorescencelifetime of a fluorescent dye that is sensitive to viscosity. The capability of the developed technique is verified by takingmeasurements in submicron thick films of two model fluids confined in a ball on flat contact. Viscosity measurements weresuccessfully performed at pressures up to 1.2 GPa and shear rates up to 105s-1. Spatial heterogeneity in viscosity caused byvariations in pressure within the thin fluid film could be observed using the technique. It was also possible to detectdifferences in the rheological responses of a Newtonian and a non-Newtonian fluid. These first in-situ high pressure, highshear viscosity measurements demonstrate the versatility of the proposed technique in providing information on theviscosity in conditions where contemporary techniques are insufficient. More importantly it highlights the complexity of therheology of engineering fluids and provides a means of verifying existing theories by performing in-situ measurements.Information on local viscosity is crucial for understanding the physics of confined fluids and to facilitate improvements inengineering technology.
AU - Ponjavic,A
AU - Dench,J
AU - Morgan,N
AU - Wong,J
DO - 10.1039/C5RA19245E
EP - 99593
PY - 2015///
SN - 2046-2069
SP - 99585
TI - In situ viscosity measurement of confined liquids
T2 - RSC Advances
UR - http://dx.doi.org/10.1039/C5RA19245E
UR - http://hdl.handle.net/10044/1/27659
VL - 5
ER -