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Pressure drop

About: Pressure drop is a(n) research topic. Over the lifetime, 36138 publication(s) have been published within this topic receiving 582812 citation(s). The topic is also known as: drop of pressure. more


Open accessBook
01 Jan 1955-
Abstract: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part. These actual flows show a special characteristic, denoted as turbulence. The character of a turbulent flow is most easily understood the case of the pipe flow. Consider the flow through a straight pipe of circular cross section and with a smooth wall. For laminar flow each fluid particle moves with uniform velocity along a rectilinear path. Because of viscosity, the velocity of the particles near the wall is smaller than that of the particles at the center. i% order to maintain the motion, a pressure decrease is required which, for laminar flow, is proportional to the first power of the mean flow velocity. Actually, however, one ob~erves that, for larger Reynolds numbers, the pressure drop increases almost with the square of the velocity and is very much larger then that given by the Hagen Poiseuille law. One may conclude that the actual flow is very different from that of the Poiseuille flow. more

Topics: Laminar flow (71%), Turbulence (69%), Pipe flow (67%) more

17,189 Citations

Open accessBook
01 Jan 1994-
Abstract: Introduction 1. The basic models 2. Empirical treatments of two-phase flow 3. Introduction to convective boiling 4. Subcooled boiling heat transfer 5. Void fraction and pressure drop in subcooled boiling 6. Saturated boiling heat transfer 7. Critical heat flux in forced convective flow - 1. Vertical uniformly heated tubes 8. Critical heat flux in forced convective flow - 2. More complex situations 9. Condensation 10. Conditions influencing the performance of boiling and condensing systems 11. Multi-component boiling and condensation Appendix Index more

Topics: Boiling (76%), Critical heat flux (62%), Subcooling (59%) more

2,424 Citations

Journal ArticleDOI: 10.1017/S0022112061000160
Francis P. Bretherton1Institutions (1)
Abstract: A long bubble of a fluid of negligible viscosity is moving steadily in a tube filled with liquid of viscosity μ at small Reynolds number, the interfacial tension being σ. The angle of contact at the wall is zero. Two related problems are treated here.In the first the tube radius r is so small that gravitational effects are negligible, and theory shows that the speed U of the bubble exceeds the average speed of the fluid in the tube by an amount UW, where (This result is in error by no more than 10% provided ). The pressure drop, P, across such a bubble is given by and W is uniquely determined by conditions near the leading meniscus. The interface near the rear meniscus has a wave-like appearance. This provides a partial theory of the indicator bubble commonly used to measure liquid flowrates in capillaries. A similar theory is applicable to the two-dimensional motion round a meniscus between two parallel plates. Experimental results given here for the value of W agree well neither with theory nor with previous experiments by other workers. No explanation is given for the discrepancies.In the second problem the tube is wider, vertical, and sealed at one end. The bubble now moves under the effect of gravity, but it is shown that it will not rise at all if where ρ is the difference in density between the fluids inside and outside the bubble. If accurate to within 10%. Experiments are adduced in support of these results, though there is disagreement with previous work. more

Topics: Bubble (56%), Pressure drop (55%), Meniscus (52%) more

2,000 Citations

Open accessJournal ArticleDOI: 10.1103/PHYSREVE.62.756
01 Jul 2000-Physical Review E
Abstract: Solids dispersed in a drying drop will migrate to the edge of the drop and form a solid ring. This phenomenon produces ringlike stains and occurs for a wide range of surfaces, solvents, and solutes. Here we show that the migration is caused by an outward flow within the drop that is driven by the loss of solvent by evaporation and geometrical constraint that the drop maintain an equilibrium droplet shape with a fixed boundary. We describe a theory that predicts the flow velocity, the rate of growth of the ring, and the distribution of solute within the drop. These predictions are compared with our experimental results. more

Topics: Drop (liquid) (65%), Pressure drop (65%), Spinning drop method (64%) more

1,874 Citations

Journal ArticleDOI: 10.1039/B510841A
24 Feb 2006-Lab on a Chip
Abstract: This article describes the process of formation of droplets and bubbles in microfluidic T-junction geometries. At low capillary numbers break-up is not dominated by shear stresses: experimental results support the assertion that the dominant contribution to the dynamics of break-up arises from the pressure drop across the emerging droplet or bubble. This pressure drop results from the high resistance to flow of the continuous (carrier) fluid in the thin films that separate the droplet from the walls of the microchannel when the droplet fills almost the entire cross-section of the channel. A simple scaling relation, based on this assertion, predicts the size of droplets and bubbles produced in the T-junctions over a range of rates of flow of the two immiscible phases, the viscosity of the continuous phase, the interfacial tension, and the geometrical dimensions of the device. more

Topics: Pressure drop (57%), Flow focusing (55%), Microchannel (51%)

1,840 Citations

No. of papers in the topic in previous years

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Topic's top 5 most impactful authors

Somchai Wongwises

106 papers, 3.4K citations

Josua P. Meyer

65 papers, 995 citations

Bengt Sundén

60 papers, 1.4K citations

Faïçal Larachi

46 papers, 1.6K citations

Satish G. Kandlikar

46 papers, 2.3K citations

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