Samenvatting
Air pollution and industrial mixing processes are just two examples of processes in
which dispersion of particles in turbulent flows is of importance. Particle dispersion
can be described by means of stochastic models. For most practical flow geometries,
knowledge of Lagrangian flow statistics is necessary to determine the coefficients
present in such models. Because numerical methods are either too inaccurate or limited
to low Reynolds numbers, this thesis looks at the possibility of determining these
model coefficients by means of experiments. An inhomogeneous turbulent flow is generated
in a pipe geometry and the Lagrangian experimental technique 3D particle
tracking velocimetry (3D PTV) is used to determine Lagrangian velocity statistics.
An experimental setup for 3D PTV measurements in turbulent pipe flow is designed.
Important design parameters and the final design are discussed. 3D PTV
experiments are carried out at two moderate Reynolds numbers. Special care has
to be taken to ensure correct analysis of the measured particle tracks. Two possible
particle sampling methods to avoid biased statistics are presented. To our knowledge,
no experimentally determined Lagrangian statistics are available in literature
for turbulent pipe flow. Furthermore, the only numerical Lagrangian results are those
generated by the DNS code of Veenman as presented in [56, 62]. Eulerian as well as
Lagrangian 3D PTV results are compared with results from literature and all compared
quantities show good agreement.
A stochastic model for particle velocity is presented for the case of turbulent
pipe flow, regarding the particle acceleration as a Markov process. In this way, the
model neglects viscosity effects and is therefore not able to resolve the small scale
effects of low Reynolds number flow. It is, however, asymptotically exact for infinitely
high Reynolds numbers. The model coefficients, being the Kolmogorov constant and
damping coefficients, are determined from 3D PTV and DNS results. The model
results are in agreement with the available experimental and DNS results at the
moderate Reynolds numbers presented in this thesis. For Lagrangian results, this
agreement is restricted to times much larger than the Kolmogorov time as a result of
the Markovian assumption.
As most practical examples of turbulent flows, as well as the validity of the presented
model, are restricted to high Reynolds numbers, the real challenge is to obtain
model coefficients at high Reynolds numbers. Upper Reynolds numbers limits for the
experimental method are discussed and suggestions on how to raise these limits for
the current geometry are given.
Originele taal2  Engels 

Kwalificatie  Doctor in de Filosofie 
Toekennende instantie 

Begeleider(s)/adviseur 

Datum van toekenning  5 apr 2007 
Plaats van publicatie  Eindhoven 
Uitgever  
Gedrukte ISBN's  9789038608761 
DOI's  
Status  Gepubliceerd  2007 
Vingerafdruk Duik in de onderzoeksthema's van '3D particle tracking velocimetry and statistical analysis of turbulent pipe flow'. Samen vormen ze een unieke vingerafdruk.
Citeer dit
Walpot, R. J. E. (2007). 3D particle tracking velocimetry and statistical analysis of turbulent pipe flow. Technische Universiteit Eindhoven. https://doi.org/10.6100/IR622498