Coalescence and separation in binary collisions of liquid drops

1990 ◽  
Vol 221 ◽  
pp. 183-204 ◽  
Author(s):  
N. Ashgriz ◽  
J. Y. Poo
Keyword(s):  
Weber Number ◽  
Theoretical Models ◽  
Binary Collision ◽  
Collision Dynamics ◽  
Number Range ◽  
Liquid Drops ◽  
Binary Collisions ◽  
Different Types ◽  
Large Impact Parameter ◽  
Water Drops

An extensive experimental investigation of the binary collision dynamics of water drops for size ratios of 1. 0.75, and 0.5, for the Weber-number range of 1 to 100, and for all impact parameters is reported. Two different types of separating collisions, namely reflexive and stretching separations, are identified. Reflexive separation is found to occur for near head-on collisions, while stretching separation occurs for large-impact-parameter collisions. The boundaries between both of the separating collisions and coalescence collision are found experimentally. Theoretical models for predictions of the reflexive and stretching separation are also given.

Where is morphological complexity?

2020 ◽  
pp. 306-328
Author(s):  
Marianne Mithun
Keyword(s):  
First Language ◽  
Theoretical Models ◽  
Formal Description ◽  
Morphological Complexity ◽  
Different Types

A number of approaches have been taken to defining complexity in language. The issue is important, since underlying some theoretical models has been an assumption, sometimes explicit, sometimes unconscious, that the simplest formal description of a language naturally matches speaker knowledge. But it is not clear that complexity is the same for the analyst, the speaker, and the learner. Here the issue is explored in two languages with relative morphological complexity, but of different types, Central Pomo and Mohawk. First the speech of bilinguals with varying degrees of English dominance is compared. Next, the development of morphological complexity is traced in children learning Mohawk as a first language. The results indicate that complexity is indeed not the same for analysts, speakers, and learners, findings more in tune with abstractive models of morphology than constructive ones.

scholarly journals Breakup of the Water Sheet Formed by Two Liquid Impinging Jets

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Yakang Xia ◽  
Lyes Khezzar ◽  
Shrinivas Bojanampati ◽  
Arman Molki
Keyword(s):  
Weber Number ◽  
Reynolds Numbers ◽  
Impinging Jets ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Impingement Angle ◽  
Number Range ◽  
Breakup Length ◽  
Sheet Breakup ◽  
Visualization Experiments

Flow visualization experiments are carried out to study the flow regimes and breakup length of the water sheet generated by two impinging liquid jets from an atomizer made of two identical tubes 0.686 mm in diameter. These experiments cover liquid jet Reynolds numbers based on the pipe diameter in the range of 1541 to 5394. The effects of the jet velocities and impingement angle between the two jets on the breakup performance are studied. Four spray patterns are recognized, which are presheet formation, smooth sheet, ruffled sheet, and open-rim sheet regimes. Water sheet breakup length is found to be consistent with previous experimental and theoretical results in the lower Weber number (based on water jet diameter and velocity) range. In the relatively high Weber number range, the breakup length tends to a constant value with increasing Weber number, and some discrepancies between experimental and theoretical predictions do exist. Measured water sheet area increases with increasing liquid jet Reynolds numbers and impingement angle within the range of the current study.

scholarly journals Secondary breakup of a drop at moderate Weber numbers

2015 ◽  
Vol 471 (2177) ◽  
pp. 20140930 ◽  
Author(s):  
Mohit Jain ◽  
R. Surya Prakash ◽  
Gaurav Tomar ◽  
R. V. Ravikrishna
Keyword(s):  
Numerical Simulations ◽  
Lognormal Distribution ◽  
Weber Number ◽  
Drop Size ◽  
Density Ratio ◽  
Transition Regime ◽  
Number Range ◽  
High Density Ratio ◽  
Secondary Breakup ◽  
Good Agreement

We present volume of fluid based numerical simulations of secondary breakup of a drop with high density ratio (approx. 1000) and also perform experiments by injecting monodisperse water droplets in a continuous jet of air and capture the breakup regimes, namely, bag formation, bag-stamen, multibag and shear breakup, observed in the moderate Weber number range (20–120). We observe an interesting transition regime between bag and shear breakup for We =80, in both simulations as well as experiments, where the formation of multiple lobes, is observed, instead of a single bag, which are connected to each other via thicker rim-like threads that hold them. We show that the transition from bag to shear breakup occurs owing to the rim dynamics which shows retraction under capillary forces at We =80, whereas the rim is sheared away with flow at We =120 thus resulting in a backward facing bag. The drop characteristics and timescales obtained in simulations are in good agreement with experiments. The drop size distribution after the breakup shows bimodal nature for the single-bag breakup mode and a unimodal nature following lognormal distribution for higher Weber numbers.

A Runback Criterion for Water Drops in a Turbulent Accelerated Boundary Layer

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Edward B. White ◽  
Jason A. Schmucker
Keyword(s):  
Leading Edge ◽  
Reynolds Numbers ◽  
Critical Parameters ◽  
Challenging Problem ◽  
Aircraft Icing ◽  
Liquid Drops ◽  
Air Interface ◽  
Displacement Thickness ◽  
Water Drops ◽  
Accelerated Flow

Predicting the runback threshold for liquid drops in aerodynamic boundary layers is a challenging problem with numerous applications including aircraft icing simulations. The critical parameters that govern drop runback are investigated in this experiment by using a wind tunnel that provides a turbulent accelerated flow similar to flows near an unswept wing’s leading edge. The experiments feature water drops on aluminum with a contact angle of 70±5deg. Results show that significant water∕air interface unsteadiness precedes drop runback. This is likely due to air-flow separation in the drop wakes. For displacement-thickness-scaled Reynolds numbers ranging from 348 to 429, a constant-Weber-number runback threshold We=3.45±0.09 is found to adequately correlate the runback results.

Flow Visualization Experiments on Secondary Flow Patterns in an Isothermally Heated Curved Pipe

1987 ◽  
Vol 109 (1) ◽  
pp. 55-61 ◽  
Author(s):  
K. C. Cheng ◽  
F. P. Yuen
Keyword(s):  
Flow Visualization ◽  
Secondary Flow ◽  
Theoretical Models ◽  
Flow Patterns ◽  
Radius Of Curvature ◽  
Dean Number ◽  
Number Range ◽  
Curved Pipe ◽  
Curved Pipes ◽  
Numerical Predictions

Secondary flow patterns at the exit of a 180 deg bend (tube inside diameter d = 1.99 cm, radius of curvature Rc = 10.85 cm) are presented to illustrate the combined effects of centrifugal and buoyancy forces in hydrodynamically and thermally developing entrance region of an isothermally heated curved pipe with both parabolic and turbulent entrance velocity profiles. Three cases of upward, horizontal, and downward-curved pipe flows are studied for constant wall temperatures Tw=55–91°C, Dean number range K=22–1209 and ReRa=1.00×106–8.86×107. The flow visualization was realized by the smoke injection method. The secondary flow patterns shown are useful for future comparison with numerical predictions and confirming theoretical models. The results can be used to assess qualitatively the limit of the applicability of the existing correlation equations for laminar forced convection in isothermally heated curved pipes without buoyancy effects.

Centrifugal Compressor Surge Behaviour

1984 ◽  
Author(s):  
J. Wachter ◽  
K.-H. Rohne
Keyword(s):  
Centrifugal Compressor ◽  
Industrial Design ◽  
Theoretical Models ◽  
Transient Characteristic ◽  
Sufficient Data ◽  
System Behaviour ◽  
Different Types ◽  
Piping Systems ◽  
Compressor Surge ◽  
Surge Line

The unsteady behaviour of compressor systems near the surge line and during surge was investigated. Experimental examinations were carried out using a three stage centrifugal compressor of industrial design in different types of piping systems. The results obtained were compared with different theoretical models. It is demonstrated that the compressor system behaviour can be calculated adequately, if sufficient data concerning the transient characteristic of the compressor are available.

Acidizing Radius Design Model for Sandstone Reservoir

2011 ◽  
Vol 361-363 ◽  
pp. 433-436
Author(s):  
Bao Quan Yang ◽  
Rui Wang ◽  
Hai Rong Fu ◽  
Xiao Shi Zhang
Keyword(s):  
Economic Benefit ◽  
Field Tests ◽  
Theoretical Models ◽  
Design Model ◽  
Injection Well ◽  
Theoretical Derivation ◽  
Different Types ◽  
Sandstone Reservoir ◽  
Sandstone Reservoirs

Acidizing radius design is an important determinative factor for the economic benefit of acidizing. According to theoretical derivation on Darcy’s formula, the theoretical models of stimulation ratio and optimum acidizing radius for conventional injection well and fractured injection well are obtained. With the example of Hailaer Oilfield, the optimum acidizing radius of different types wells is obtained. This design model is applied for 7 wells in Xinanling Group of Hailaer Oilfield. The results of field tests indicate the design model is practical and can also be used to guide the acidizing design for other sandstone reservoirs.

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