**1. Introduction**

Hydrodynamic and physicochemical interactions play an important role in many industrial unit processes and hence its importance in many engineering applications of fluid flow. Fluid flow investigations in a wide range of process conditions as well as complex biological, physical and chemical processes have been the subject of many scientific publications over the past two decades. Several studies on bench, pilot and industrial scales have been conducted on a wide variety of hydrodynamic conditions and different reactor geometric designs. In many of these studies, the aim is to provide an insight into the fluid flow and process dynamics in terms of the spatial and temporal evolution within the flow device, and in some cases, performance testing of newly designed flow units and processing techniques with potential applications on

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

industrial scale. Regardless of the focus of these studies, it is quite apparent that valuable information can be obtained from the basic study of fluid flow dynamics in process units especially from design and optimization perspective.

understanding and analysis of the problem is often required. This will assist in the selection of appropriate experimental data collection methods and mathematical models that sufficiently encapsulate the physics of the problem. A number of numerical approaches and solution strategies discussed in the subsequent sections have been developed for a multitude of fluid flow scenarios. Therefore, it is important to evaluate each circumstance individually and form an opinion regarding which model would provide the best fit for a particular fluid engineering problem. It has been suggested that the robustness of any mathematical model is a function of

Hydrodynamic Characterization of Physicochemical Process in Stirred Tanks and Agglomeration Reactors

The interactions of different phases in fluid flow occur on different scales of the fluid motion as depicted in **Figure 2**. Fluid dynamics is primarily focused on the macroscopic phenomena of the fluid flow in which the fluid is treated as a continuum. For instance, a fluid element is composed of many molecules, and the fluid dynamics represent the behaviour of the numerous molecules within the system. This concept with certain assumptions forms the basis of the derivation of fluid conservation equations of mass and momentum also known as the Navier-Stokes equation using a fluid control volume [8, 9]. The general form of the governing equations of mass and momentum conservation in any fluid flow system can be written as follows (Eqs. (1) and (2)):

∂t <sup>+</sup> <sup>∇</sup><sup>∙</sup> (ρ<sup>v</sup>

<sup>→</sup>) <sup>=</sup> <sup>−</sup>∇<sup>p</sup> <sup>+</sup> <sup>∇</sup><sup>∙</sup> (τ̿

**Figure 2.** Multiscale modeling approach to fluid-particle interactions (reproduced from [14] with permissions © 2017

) + ρg <sup>→</sup> + F

<sup>→</sup>v

<sup>→</sup>) = Sm (1)

http://dx.doi.org/ 10.5772/intechopen.77014

59

<sup>→</sup> (2)

the numerical code being used and the flow scenario being modeled [7].

**2.2. Fluid dynamics and governing equations**

<sup>∂</sup>ρ\_\_

∂t(ρ<sup>v</sup>

<sup>→</sup>) + ∇∙ (ρv

\_\_<sup>∂</sup>

Springer).

A quick survey of the studies in this field shows that many innovative process reactors have been successfully tested on different scales for a wide variety of technical applications ranging from fine particle separation and water purification to cell culture preparation [1–6]. Experimental data, which are collected in these studies for numerical validation purposes, are often used to characterize the hydrodynamic behaviour as well as to quantify the fluid parameters of interest such as the flow velocity profile, vorticity, turbulent kinetic energy and its rate of dissipation, turbulent intensity, and so on. While there is a large body of scientific literature focusing on the hydrodynamics and physicochemical processes in stirred tank reactors, the aim of the present communication is to briefly summarize developments in this field especially in the application of the knowledge of the fluid dynamics to fluid-particle reactor design, development and optimization.
