Fascinating dynamics is known to result when the flow rate Q at which water drips from a faucet varies. Starting with simple (period-1) dripping, the system transitions as Q increases to complex dripping, where it exhibits period-n (n=2,4, em leader ) and chaotic responses, and then jets once Q exceeds a threshold. New experiments and simulations show that high viscosity (micro) liquids, e.g., syrup, transition directly from simple dripping to jetting as Q increases. Phase diagrams showing transitions between simple and complex dripping and jetting in (Q,micro) space are developed. Values of Q for transition from dripping to jetting are estimated from scaling arguments and shown to accord well with simulations.

Continuous emission of drops of an incompressible Newtonian liquid from a tube–dripping–is a much studied problem because it is important in applications as diverse as inkjet printing, microarraying, and microencapsulation, and recognized as the prototypical nonlinear dynamical system, viz., the leaky faucet. The faucet’s dynamics are studied in this paper by a combination of experiment, using high-speed imaging, and computation, in which the one-dimensional slender-jet equations are solved numerically by finite element analysis, over ranges of the governing parameters that have heretofore been unexplored. Previous studies when the Bond number G that measures the relative importance of gravitational to surface tension force is moderate, G≈0.5, and the Ohnesorge number Oh that measures the relative importance of viscous to surface tension force is low, Oh≈0.1, have shown that the dynamics changes from (a) simple dripping, i.e., period-1 dripping with or without satellites, to (b) complex dripping, where the system exhibits period doubling bifurcations and hysteresis, to (c) jetting, as the Weber number We that measures the relative importance of inertial to surface tension force increases. New experiments and computations reveal that lowering the Bond number to G≈0.3 while holding Oh fixed results in profound simplification of the behavior of the faucet. At the lower value of G, the faucet exhibits simply period-1 dripping, period-2 dripping, and jetting as We increases. Experimental and computational bifurcation diagrams when G≈0.3 and Oh≈0.1 that depict the variation of drop length or volume at breakup with We are reported and shown to agree well with each other. The range of We over which the faucet exhibits complex dripping when G≈0.3 is shown by both experiment and computation to shrink as Oh increases. Computations are also used to develop a comprehensive phase diagram when G≈0.3 that shows transitions between simple dripping and complex dripping, and those between dripping and jetting in (We,Oh) space. Similar to the case of G≈0.5, dripping faucets of high viscosity (Oh) liquids are shown to transition directly from simple dripping to jetting without exhibiting complex dripping when G≈0.3. When G≈0.3, computed values of We that signal transition from dripping to jetting are further shown to accord well with estimates obtained from scaling analyses. By contrast, new computations in which the Bond number is increased to G≈1, while Oh is held fixed at Oh≈0.1, reveal that the faucet’s response becomes quite complex for large G. In such situations, the computations predict theoretical occurrence of (a) rare period-3 dripping and period-3 intermittence, which have previously been surmised solely by the use of ad hoc spring-mass models of dripping, and (b) chaotic attractors. Therefore, by combining insights from earlier studies and the detailed response of dripping which has been obtained here by varying (i) Oh as 0.01⩽Oh⩽2, a range that is typical of most practical applications, (ii) We from virtually zero to a value just exceeding that at which the system transitions from dripping to jetting, and (iii) G from a small value to a value approaching that beyond which controlled formation of drops is prohibited, this paper provides a comprehensive understanding of the effect of the governing parameters on the nonlinear dynamics of dripping.

Asphaltenes tend to deposit in reservoir, well tubing, flow lines, separators, etc., causing significant production losses. Asphaltenes are originally stable in crude oil at reservoir conditions. However, changes in temperature, pressure, and/or composition may cause asphaltenes to precipitate and potentially deposit onto the surfaces of a flowing conduit. There are several publications in the literature that discuss modeling of asphaltene phase behavior in oil as well as development of deposition models to simulate asphaltene deposition profiles along a flow path. In this paper, a previously reported asphaltene deposition tool (ADEPT) is used to study the deposition in a subsea pipeline in the Gulf of Mexico. This is the first demonstration of an asphaltene deposition simulator that has been used in a fully predictive manner. All of the required kinetic parameters used for deposition predictions were experimentally measured. A new methodology to scale up the deposition constant measured from a small-scale capillary deposition experiment to a large-scale subsea flow line is also reported in this paper. The predictions that made use of such an appropriately scaled deposition constant were in good agreement with field observations. The simulator was also able to predict the effects of a decreasing deposit thickness with increasing flow rates as observed in the Hassi Messaoud field. The paper further discusses a modified pseudo-transient simulator that is capable of incorporating the effect of deposit buildup on flow velocities and frictional pressure drop, which, in turn, affects the phase behavior of asphaltene. The differences between ADEPT and the pseudo-transient simulator is discussed. Simulation results show that incorporating the effect of deposit buildup causes a decrease in deposition rates with time, as reported from field observations.

We determined and fine‐tuned the solids transport models appropriate for predicting the single‐phase carrier fluid velocity to transport solid particles in conduits for horizontal, low concentration flow. A database with 538 experimental data points was compiled. A literature review was performed to determine the data ranges, forces, and mechanisms used to develop 44 models, and their velocity predictions were compared against the database using statistics. Using the dimensionless forms of the models and the data, the model parameters were adjusted to improve their accuracy and identify the dominant forces. At low concentrations: for liquid/solid flow from a bed of solids and gas/solid flow from the bottom of pipelines, the particle weight, and inertial and viscous forces dominate; for gas/solid flow from a bed of solids, the particle weight, and inertial, viscous, and adhesive forces play a role; and gaps exist in the data for large‐diameter pipes and high‐density gases. © 2013 American Institute of Chemical Engineers AIChE J, 60: 76–122, 2014

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