*5.5.2 Oscillatory flow vortex pattern (e.g., oscillatory reactor)*

An oscillator is a device whose action causes intermittent velocity gradients over time, space, and direction, and can be used for colloid removal based on physical flow manipulation. An oscillatory flow pattern is commonly found in reactors with an enclosed flow induced by an oscillator. Results from previous studies have shown that gentle oscillation can promote simultaneous flocculation and particle agglomeration over a relatively short periods of time [42]. This technique, whose implementation can result in reductions of the reactor sizes and process times, has a strong potential to improve conventional separation processes. It has also been observed that higher oscillating frequency promotes faster upward vertical velocities, resulting in different sedimentation patterns and removal efficiencies generated by the different oscillation frequencies [43].

**15**

*The Role of Micro Vortex in the Environmental and Biological Processes*

*5.5.3 Swirling flow vortex pattern (e.g., stirred tank, hydrocyclone)*

tion of the impeller shape for a particular vessel geometry [61, 62].

This brief communication is a summary of the main concepts involved the fluid-particle research and technical applications. It is by no means an exhaustive contribution and readers interested in the details of the subject-matter are advised to consult other scientific information available on the subject-matter. The fluid process engineering is a field of active research and the there is an ever-increasing scope for the application of hydrodynamics, turbulence, and vortex dynamics. In addition to the identified areas of application, there are several emerging areas of application. As the turbulence research advance with better computing power and algorithms, it is hoped that there will be limitless scope for the application of vortex

A swirling type of flow pattern is commonly found in hydrocyclone [55–57] and counter-rotating reactors with an enclosed flow induced by a rotational swirling effect [58, 59]. In addition to hydrocyclone, this type of flow field is also common in rotating reactors with baffles such as mixing tank, in which case, the flow is a combination of rotational and swirl dominated flow as shown in **Figure 6c**. In the case of a counter-rotating vortex reactor, it has also been found that the swirl ratio and micromixing time of the flow increases as the vortex reactor (MIVR) is scaled up, indicating a flow with stronger swirl yet less mixing efficiency [60]. In order to promote mixing and enhance the floc formation process, some baffles should be installed to break water flow co-rotation with the impeller [54]. In modifying the flow pattern to suit a particular condition, it is advisable to perform the optimiza-

*DOI: http://dx.doi.org/10.5772/intechopen.93531*

**6. Conclusions and future perspectives**

dynamics in fluid process engineering.

The authors declare no conflict of interest.

DWDS drinking water distribution systems

HCR hydrodynamic cavitation reactor

APFD aeration plug-flow device COD chemical oxygen demand DBPs disinfection byproducts DO dissolved oxygen

HC hydrodynamic cavitation

HAAs haloacetic acids

THMs trihalomethanes

**Conflict of interest**

**Nomenclature**

#### **Figure 6.**

*Typical cross-sections of vortex patterns in fluid-particle reactors (a) rotatory-type flow field (b) oscillatory-type flow field (c) swirling-type flow field.*

*The Role of Micro Vortex in the Environmental and Biological Processes DOI: http://dx.doi.org/10.5772/intechopen.93531*
