Multiple drop impacts

Abstract Spray-wall impact is an important process in numerous applications such as internal combustion (IC) engines, spray cooling, painting, metallurgy, and many others. This chapter reviews the main challenges in this dynamic thermofluid event and attempts to systematize the knowledge developed in the hydrodynamics of multiple drop impacts and liquid deposition, the statistical analysis of secondary atomization after impact, and the thermodynamics underlying heat transfer processes in spray impaction onto heated surfaces. 

Keywords Atomization Correlations DepositiOTi E>rop Interaction Heat transfer Impinging spray Liquid deposition Multiple drop impacts Secondary thermodynamics Spray Spray-wall impact Statistics... 

The experiments reported in the literature explore the outcome of those interactions studying the influence of length and time scales associated with multiple drop impacts on the outcome, as described in Fig. 21.2. 

Fig. 21.2 Scale parameters involved in multiple drop impacts...

The appUcatitHi of spray-wall impact to engineering systems relies on the accurate knowledge of four research subjects (1) multiple drop impacts (2) liquid deposition (3) secondary atomization and (4) heat transfer on spray impaction. 

Roisman I V, Prunet-Foch B, Tropea C, Vignes-Adler M (2002) Multiple drop impact onto a dry solid substrate. Journal of Colloid and Interface Science 256 396-410. 

Abstract Among the noncontinuum-based computational techniques, the lattice Boltzman method (LBM) has received considerable attention recently. In this chapter, we will briefly present the main elements of the LBM, which has evolved as a minimal kinetic method for fluid dynamics, focusing in particular, on multiphase flow modeling. We will then discuss some of its recent developments based on the multiple-relaxation-time formulation and consistent discretizatirai strategies for enhanced numerical stability, high viscosity contrasts, and density ratios for simulation of interfacial instabilities and multiphase flow problems. As examples, numerical investigations of drop collisions, jet break-up, and drop impact on walls will be presented. We will also outline some future directions for further development of the LBM for applications related to interfacial instabilities and sprays. 

Cossali GE, Marengo M, Santini M (2004a) Impact of single and multiple drop array on a liquid film. In Proceedings of the 19th ILASS-Eiffope, Nottingham. 

Reviewing the overhead water wash most overhead condensers are washed continually to minimize fouling. Since multiple bundles are common, solenoids and a PLX3 can be used to wash one bundle at a time, for approximately ten minutes each. This can lower the pressure drop and increase the available cooling with minimal impact. 

The impact of secondary aerosols on indirect radiative forcing is the most variable and is the least understood [3]. The reasons why the indirect effect of secondary aerosols is so difficult to describe is that it depends upon [1] (1) a series of molecular-microphysical processes that connect aerosol nucleation to cloud condensation nuclei to cloud drops and then ultimately to cloud albedo and (2) complex cloud-scale dynamics on scales of 100-1000 km involve a consistent matching of multiple spatial and time scales and are extremely difficult to parameterize and incorporate in climate models. Nucleation changes aerosol particle concentrations that cause changes in cloud droplet concentrations, which in turn, alter cloud albedo. Thus, macro-scale cloud properties that influence indirect forcing result from both micro-scale and large-scale dynamics. To date, the micro-scale chemical physics has not received the appropriate attention. 

In some instances the ball is dropped by allowing it to roll off an inclined track and is, therefore, rotating when it hits the sample. In the case of a no-fire, the ball bounces away from the block and only impacts the sample once, thus overcoming one of the inherent problems of multiple impacts produced by drop hammers. In other cases the ball is retained at the drop height and is released electromagnetically. The ease of sample testing, the low cost of the expendable... 

Provide warning systems which allow the crew to immediately recognise the problem and take appropriate corrective action. Consider the implication of multiple simultaneous warning (e.g. from cascade failures) and their impact on crew workload and performance (see Chapter 10). Ensure that the pilot is kept in the loop . For instance, an autopilot may automatically cope with a series of developing problems without informing the crew. When it reaches a point where the autopilot cannot control the aircraft, it may then suddenly drop a complex situation in the lap of the pilot. 

Our main interest in this chapter is to get a better understanding of inventory risk allocation issues in drop-shipping supply chains as well as the impact of power distribution between the channel entities. To keep focus and to not diffuse economic insights, we do not explicitly reflect other issues encountered in e-commerce fulfillment, since many are hard to include in a formal model. Among these issues are possible differences in transportation costs and responsiveness, coordination issues arising when multiple wholesalers are needed to fulfill a single order, and the rationing of inventory when a wholesaler serves multiple retailers. These and other issues are treated qualitatively in Randall et al. (2002). 

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