# Knowledge base: Warsaw University of Technology

Back

## Modeling of non-Newtonian fluid mixing in pipe mixer with chaotic flow

### Barbara Kazimiera Siekierska

#### Abstract

Mixing is a process of equalization of composition and temperature of a fluid in a system. It is among the most common processes in the chemical industry. Mixing relays on moving of fluid elements of different composition, temperature and different age against one another, which is accompanied by molecular and turbulent diffusion. Mixing in the laminar flow proceeds much slowly than in the turbulent flow but laminar mixing can be speeded up by an onset of chaotic advection in the system. Then a fully deterministic laminar flow, in an Eulerian frame of reference, generates an irregular spatial distribution of trajectories of fluid particles in the system. The influence of non-Newtonian properties of fluid on mixing has been analyzed in this paper. This influence was studied using numerical simulation of a laminar, isothermal and steady flow of Newtonian and non-Newtonian fluids, the latter described by Carreau model. The numerical simulations were carried out for a pipe mixer with a complicated geometry. Defining computational problem was the first step in this work. This phase of the work consisted of: defining the precise geometry of the analyzed pipe mixer, defining initial and boundary conditions, an assumption of physiochemical properties of the mixed fluids. Then computational grid was made which means that the volume of pipe mixer was discretized into smaller volume elements. A velocity field was calculated, a secondary flow pattern was identyfied in the second phase of this work. Poincare maps were prepared to visualize the dispersion of marker particles in several cross-sections of the pipe mixer. The history of changes of the shear rate, deformation rate of material surface and energetic efficiency of mixing along mixer were also calculated and compared in this step. Results of this study let come to some important conclusions. Non-Newtonian properties of a fluid makes generation of chaos more difficult. It has lots in common with mixing because a stronger chaos in a system means better mixing. Non-Newtonian properties have negative effect on macromixing. On the other hand comparison of an average energetic efficiencies of mixing for Newtonian and non-Newtonian fluids suggests that for time constant of Carreau model � � 0,2 optimal value of the flow behavior index � between 0,1 and 1 exists. In this range of � micromixing is the most effective.
Record ID
WUT2a4892bffd48435fb4794f855670389e
Diploma type
Master of Science
Author
Barbara Kazimiera Siekierska (FCPE) Barbara Kazimiera Siekierska,, Faculty of Chemical and Process Engineering (FCPE)
Title in Polish
Modelowanie mieszania cieczy nienewtonowskich w mieszalniku rurowym z przepływem chaotycznym
Supervisor
Antoni Rożeń (FCPE/DCRED) Antoni Rożeń,, Department of Chemical Reactor Engineering and Dynamics (FCPE/DCRED)Faculty of Chemical and Process Engineering (FCPE)
Certifying unit
Faculty of Chemical and Process Engineering (FCPE)
Affiliation unit
Department of Chemical Reactor Engineering and Dynamics (FCPE/DCRED)
Study subject / specialization
, Inżynieria Chemiczna i Procesowa
Language
(pl) Polish
Status
Finished
Defense Date
12-06-2012
Issue date (year)
2012
Pages
76
Internal identifier
DICHP-2138
Reviewers
Antoni Rożeń (FCPE/DCRED) Antoni Rożeń,, Department of Chemical Reactor Engineering and Dynamics (FCPE/DCRED)Faculty of Chemical and Process Engineering (FCPE) Arkadiusz Moskal (FCPE/CIPE) Arkadiusz Moskal,, Chair of Integrated Process Engineering (FCPE/CIPE)Faculty of Chemical and Process Engineering (FCPE)
Keywords in Polish
-
Keywords in English
-
Abstract in Polish
File
• File: 1
praca magisterska.pdf
Request a WCAG compliant version
Local fields
Identyfikator pracy APD: 6721

Uniform Resource Identifier
https://repo.pw.edu.pl/info/master/WUT2a4892bffd48435fb4794f855670389e/
URN
urn:pw-repo:WUT2a4892bffd48435fb4794f855670389e

Confirmation
Are you sure?