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A mathematical model has been presented for a high speed liquid jet penetration into soft solid by a needle-free injection system. The model consists of a cylindrical column formed by the initial jet penetration and an expansion sphere due to continuous deposition of the liquid. By solving the equations of energy conservation and volume conservation, the penetration depth and the radius of the expansion sphere can be predicted. As an example, the calculation results were presented for a typical needle-free injection system into which a silicon rubber was injected into. The calculation results were compared with the experimental results. [DOI: 10.1115/1.4002487] Keywords: modeling, jet, injection, needle-free, penetration

The characteristics of a turbulent jet issuing from a square cross section nozzle in the vicinity of a free surface are presented. Two-component laser Doppler measurements were obtained at eight stations downstream of the nozzle exit, up to a distance of 27 nozzle widths. The Reynolds number based on the exit condition was 40,000. The proximity of the free surface influence the turbulence levels in the jet. Both confinement effects and axis switching influence the evolution of the velocity profiles downstream of the nozzle. The shear stress profiles indicate the formation of a wider mixing zone in the bottom portion of the jet in regions closer to the nozzle exit. Through quadrant decomposition, ejection, and entraining type events were identified. The magnitudes of the peak shear stress in the various quadrants indicate differences in the turbulence characteristics on the top and bottom portions of the jet. As distinguished in the extreme event plots, there are differences in the magnitudes of the peaks and also in their locations. DOI: 10.1061/(ASCE)0733-9429(2009)135:11(989) CE Database subject headings: Hydraulic jets; Submerged jets; Turbulent flow; Mixing; Free surfaces.

The present study is to parameterize the influence of regular progressive waves on the diffusion of a neutrally buoyant turbulent round jet experimentally. The jet, located at the middepth, discharges into the wave field horizontally in the direction against the wave propagation. The particle image velocimetry technique and the laser induced fluorescence technique were used to measure the velocity field and examine the jet cross-sectional profile. Three different wave periods with a range of wave amplitudes in each wave period were tested to investigate the effect of waves on jet diffusion. The wave conditions cover both the shallow water and deep water, whereas the wave slopes range from linear to weakly nonlinear. The results showed that the width of the jet was significantly affected by the waves. The wave dispersion enhanced the jet diffusion, especially for a larger wave slope and a shallower water depth. The results also showed that the wave-to-jet momentum ratio is the most important parameter to characterize the effect of waves to the diffusion of jet. DOI: 10.1061/(ASCE)0733-950X(2009) 135:3(100) CE Database subject headings: Water waves; Buoyant jets; Coastal environment; Turbulent diffusion; Dispersion.

Experiments were carried out to investigate the behavior of horizontal gas-liquid injection in a water tank. Measurements of bubble properties and mean liquid flow structure were obtained. The turbulence in the liquid phase appears to help generating bubbles with relatively uniform diameters of 1-4 mm. Both bubble properties and mean liquid flow structure depended on the gas volume fraction and the densimetric Froude number at the nozzle exit. It was found that the bubbles strongly affected the trajectory of the water jet, which behaved similarly to single-phase buoyant jets. However, at gas volume fractions smaller than about 0.15, the water jet completely separated from the bubble core. Bubble slip velocity was also found to be higher than the terminal velocity for isolated bubbles reported in the literature. Dimensionless correlations were proposed to describe bubble characteristics and the trajectory of the bubble plumes and water jets as a function of the gas volume fraction and the densimetric Froude number. Finally, applications of the results for aeration/ mixing purposes are presented. DOI: 10.1061/(ASCE)0733-9429(2008)134:12(1722) CE Database subject headings: Aeration; Bubbles; Jets; Mixing; Plumes; Gas; Water tanks; Froude number.

The energy loss of the vertical drop with subcritical flow in the upstream channel has been studied experimentally with a physical model of 0.20 m drop height. Experimental data were collected in a range where few data exist. Based on a similarity between a turbulent surface jet and the flow over the drop, a model is developed using the theories of the shear layer and fully developed surface jet to estimate the energy loss. The results were compared with previous and current experimental data and were found to agree well with the proposed model. CE Database subject headings: Hydraulic structures; Subcritical flow; Energy; Hydraulic jets; Turbulence; Experimental data.

Laboratory and computational fluid dynamics (CFD) model studies with turbulent, plane, particle-laden buoyant jets discharged horizontally into a quiescent ambient fluid have demonstrated that the presence of particles has no significant influence upon the buoyant jet trajectories over a wide range of forcing conditions and source concentrations of 0.1% or less. Bed deposition distributions show a large initial maximum close to the source, indicative of a dominant, localized particle fall-out from the buoyant jet margins. Beyond this near-source region, the distributions show a gradual decrease in particle deposition with increasing distance from the source, as a result of particle fall-out from the spreading surface layer generated by the buoyant jet impinging on the free surface of the receiving waters. In both cases, the deposition distributions scale well with the nondimensional settling parameter [w.sub.s]/[b.sup.1/3.sub.0] and the source Froude number [F.sub.0]. CFD simulations show good agreement with the laboratory data, particularly for deposition distributions downstream of the source. Additionally, the simulations indicate clearly that the receiving water boundaries can produce significant secondary return flows through fluid displacement by the spreading surface gravity current and its subsequent reflection. DOI: 10.1061/(ASCE)0733-9429(2008)134:8(1110) CE Database subject headings: Buoyant jets; Turbulent jets; Sediment; Discharge; Deposition; Outfall sewers.

Ambient flow field and circulation patterns induced by circular bubble plumes and water jets in tanks of different sizes were studied in rectangular and square water tanks. A nonstationary nature of the flow was observed in all experiments and its dominant oscillation frequency was found to directly relate to the tank size. The flow circulation patterns were similar for bubble plumes and water jets, but changed significantly with tank size and geometry. Strong three-dimensional effects were observed in a rectangular tank, resulting in flow entraining in the longer plane and flow detraining in the shorter plane, especially for the bubble plume tests. A relationship was developed to relate the tank size to the patterns of circulation cells. Nearly isotropic turbulent flow conditions were obtained in all experiments, but the effect of tank size and geometry on the magnitude of the turbulent stresses was more pronounced in the bubble plume tests. DOI: 10.1061/(ASCE)0733-9429(2008)134:6(833) CE Database subject headings: Bubbles; Water circulation; Water tanks; Water jets; Mixing; Plumes; Geometry; Turbulent flow.

A single-jet water meter was modeled and simulated within a wide measuring range that included flow rates in laminar, transitional, and turbulent flow regimes. The interaction between the turbine and the flow, on which the operating principle of this kind of meter is based, was studied in depth from the detailed information provided by simulations of the three dimensional flow within the meter. This interaction was resolved by means of a devised semi-implicit time-marching procedure in such a way that the speed and the position of the turbine were obtained as part of the solution. Results obtained regarding the turbine's mean rotation speed, measurement error, and pressure drop were validated through experimental measurements performed on a test rig. The role of mechanical friction on the performance of the meter at low flow rates was analyzed and interesting conclusions about its influence on the reduction of the turbine's rotation speed and on the related change in the measurement error were drawn. The mathematical model developed was capable of reproducing the performance of the meter throughout the majority of the measuring range, and thus was shown to be a very valuable tool for the analysis and improvement of the single-jet water meter studied. Keywords: single-jet water meter, CFD, fluid-structure interaction, measurement error, pressure drop, mechanical friction

Results are presented from a series of laboratory experiments investigating the characteristic features of particle-laden, round, turbulent, buoyant jets discharged horizontally into stationary and coflowing receiving fluids. For the volumetric source concentrations of particles tested (~ 0.1%), the presence of the particle load was found to have no significant influence on mean buoyant jet trajectories. Deposition patterns on the bed of the receiving water container indicated the existence of two separate sedimentation processes for discharges into stationary or coflowing ambients, namely (1) a relatively concentrated, narrow band of particle accumulation associated with near-source fallout from the buoyant jet margins; and (2) a broader and more disperse downstream depositional fan associated with particle fallout from the radially-expanding surface gravity current formed by the impingement of the buoyant jet with the free surface of the receiving fluid. Scaling arguments have been developed and applied successfully to deposition length scales associated with these sedimentation patterns, allowing the quantitative characteristics and parametric dependences of the deposition distributions to be established. DOI: 10.1061/(ASCE)0733-9429(2008)134:4(390) CE Database subject headings: Buoyant jets; Sedimentation; Sediment discharge; Outfall sewers; Wastewater management; Sediment deposits.

Several flights were conducted by the University of Wyoming King Air near Cape Mendocino, California, during June 2004 to examine finescale features of the coastal low-level jet (CJ) that frequently forms during summer over the ocean off the West Coast of the United States. The primary goal of these flights was to measure the horizontal pressure gradient force (PGF) and hence to determine the forcing of the CJ directly. By flying a series of redundant legs on an isobaric surface, heights of the pressure surface can be obtained from radar altimeter measurements and refined position estimates from an onboard global positioning system receiver. The slope of the isobaric surface height is proportional to the PGF. Results are shown for the 22 June 2004 case study conducted to the south of Cape Mendocino. The forcing of a CJ under weak synoptic forcing and the role of the elevated terrain near Cape Mendocino are explored. Ten isobaric legs approximately 70 km in length and directed east-west were conducted near the level of the maximum CJ wind speed. The vertical structure of the CJ was obtained from sawtooth legs conducted along an east-west flight leg. Numerical simulations have been performed for this case using the fifth-generation Pennsylvania State University National Center for Atmospheric Research Mesoscale Model (MM5) for comparison with in situ measurements. Model simulations show pressure perturbations in the vicinity of the cape as the northerly winds associated with the CJ interact with the coastal topography. Close agreement is found between in situ measurements and MM5 analyses of the various state parameters and the PGF along the east-west flight track in the lee of Cape Mendocino. Strong variation in the PGF is observed along the flight path. Large ageostrophic accelerations are present in response to the adjustment of the CJ with Cape Mendocino, reflecting the force imbalance between the observed PGF and Coriolis force.

The concept of multiple droplet impacts resulting from ultra high-pressure waterjet (UHPWJ) was used to develop a mathematical model to describe the effect of interfacial pressure on the underlying workpiece material A non-linear elastic-plastic finite element analysis (FEA) was carried out in this study using the interfacial pressure model to predict residual compressive stresses. This three-dimensional FEA model was based on quasi-static considerations to provide prediction of both magnitude and depth of residual stress fields in a 7075-T6 aluminum alloy (A17075-T6). Results of the FEA modeling were in good agreement with experimental measurements. Effects of applied pressures on the residual stress fields are also presented and discussed as a method of estimating high-pressure waterjet induced compressive stresses under varying process conditions for peening.

This paper presents the images of a long gap discharge induced by a water jet. Spherical metal balls of 5-cm diameter were used as high-voltage, ground, and guiding electrodes. The distance between the high-voltage electrode and the ground one was 50 cm, and the distance between the high-voltage electrode and the guiding one was set to 75 cm. A tap water of 50 [OMEGA] x m resistivity was jetted from behind the guiding electrode toward the high-voltage electrode. A lightning impulse voltage of 1/40 [micro]s generated with an impulse generator was applied to the high-voltage electrode. The leader discharge developed from the tip of the water jet toward the high-voltage electrode. After the discharge bridged between the water jet and the high-voltage electrode, the discharge developed along the water jet. Index Terms--Leader development, long gap discharge, streamer discharge, surface discharge, triggered lightning, water jet.