Hydrodynamic cavitation bubble behavior

Acoustic cavitation is as a result of the passage of ultrasound through the medium, while hydrodynamic cavitation occurs as the result of the velocity variation in the flow due to the changing geometry of the path of fluid flow. In spite of this difference in the mechanisms of generation of two types of cavitation, bubble behavior shows similar trends with the variation of parameters in both these types of cavitation. The two main aspects of bubble behavior in cavitation phenomena are ... 

Moholkar VS, Pandit AB (1997) Bubble behavior in hydrodynamic cavitation Effect of turbulence. AIChE J 43 1641-1648... 

Further investigations of chemical kinetics and transformation products will be carried out during the final phase of the project. In order to truly understand sonochemical effects, the behavior of the individual bubbles and the bubble clouds must be more finely resolved. Physical characterization of cavitation bubble clouds will also be performed. Thus, a more fundamental link will be established between bulk, observable parameters and sonochemistry, via the physics and hydrodynamics of the cavitating cloud. 

Perhaps the most significant feature of hydrodynamic cavitation is that as the flow changes from nonturbulent to turbulent, bubble behavior changes from oscillatory to transient, and the latter resembles acoustic cavitation. Thus features similar to those of acoustic cavitation can be replicated in hydrodynamic flow by manipulating the level of turbulence. 

Analysis on the Basis of Bubble Dynamics The bubble behavior and hence the pressure pulse generated at the collapse of the cavity in the case of hydrodynamic cavitation depends upon the operating conditions as well as the geometry of the mechanical constriction that results in the generation of cavitating conditions downstream of the orifice. Thus, as a first step towards the design of hydrodynamic-cavitation reactors, it is important to understand the relationship between the cavity behavior and the operating parameters and possibly quantify the intensity of cavitation and then the net cavitational effects as a direct function... 

Cavitation is defined as the formation and behavior of gas or vapor bubbles and bubble clouds in a liquid. It can be induced thermally (by boiling), acoustically, optically (with a laser), by high energy charged particles, and hydrodynamically, i.e., through a pressure fall in a flow. The first questions that arise are (1) what are the processes inducing cavitation, (2) how does a bubble evolve from its formation up to its demise, (3) what occurs inside collapsing bubbles so that they are able to produce radicals and excited species, (4) what is the nature of the interactions between bubbles and solid boundaries involved in the dramatic erosion of these solids ... 

---