Flow and mixing of complex fluids

Al-Sharify, Zainab Talib Abidzaid (2017). Flow and mixing of complex fluids. University of Birmingham. Ph.D.

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Abstract

The mixing of complex fluids in stirred reactors is widly used in many industries. Mechanically agitated vessels are widely used in these industries such as wastewater treatment, pharmaceuticals, nuclear and food processing. Complex fluids are frequently encountered in these industries. There is growing interest in developing and studying these fluids, especially for those of shear thickening (ST) behaviour, due to the importance of their industrial applications such as flexible body armor and force damping applications which can protect a person from danger or risk and ultimately saveone’s life. Little work has been done to understand how to mix complex fluids effectively, mainly because of their opaque nature. In this thesis, new ST fluids formulations were developed and these fluids were used as a model fluid for mixing studies. The flow field in an opaque ST fluid was determined experimentally using the positron emission particle tracking (PEPT). In addition, the performance of axial, radial and mixed flow impellers in mixing complex fluids have been also studied using different experimental techniques and the computational fluid dynamics (CFD) simulations. Moreover, for the first time, PEPT has been used to investigate the flow field of floating particles in a stirred vessel. PEPT was used to investigate the two-phase flow field inside a stirred vessel of polypropylene particles in different types of rheological fluids, at the just drawdown speed for a wide range of solid concentrations from 1.8 vol% up to 46 vol%.

The outcomes of this thesis are beneficial to many chemical processes, such as e.g. formulation processes in the pharmaceutical industry, whereby an essential step in the product development involving powder mixing is the ability to drawdown the floating solids. In addition, the outcome of this thesis can also be beneficial in identifying the ideal configuration of stirred vessels used in chemical processes where mixing is the central feature, for example, in the food and rubber industries. Moreover, the newly developed complex fluids (shear thickening fluids) can be used in many industrial and commercial applications such as in the defence industry (as liquid body armor) and also as part of the protective devices designed to minimise head and neck injuries that occur in some sports accidents such as in car racing, football, ice hockey etc.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):