Buoyant Jets Discharging Nonvertically Into a Uniform, Quiescent Ambient—A Finite-Difference Analysis and Turbulence Modeling

Madni, I.K.; Pletcher, Richard H.

doi:10.1115/1.3450755

Cited by 15 publications

(4 citation statements)

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“…However, a similar treatment may be carried out for turbulent flow, employing a suitable closure model. For the eddy-viscosity model, a is replaced by a + eH and v by v + e M , where eH and eM are eddy diffusivity and viscosity respectively, as outlined by Madni & Pletcher (1977). Though additional parameters arise due to the turbulence modelling employed, the basic governing parameters are still the same as those for laminar flow.…”

Section: _ -mentioning

confidence: 99%

Effect of opposing buoyancy on the flow in free and wall jets

Goldman

Jaluria

1986

J. Fluid Mech.

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An experimental investigation is carried out into the characteristics of the velocity and thermal fields in free and wall jets in which the buoyancy force opposes the flow. The flow configuration considered is that of a negatively buoyant two-dimensional jet discharged adjacent to a vertical surface, as well as that discharged away from the boundaries of the region. Such convective flows are frequently encountered in heat-rejection processes and in enclosure fires, where, at various locations, the buoyancy force is upward while the flow is downward, resulting in negative buoyancy. An experimental system is developed to study the downward penetration of such jets in which the buoyancy force opposes the externally induced flow. The penetration distance is measured and related to the inflow conditions, particularly the temperature and velocity at the discharge location. A steady state is simulated by allowing the fluid to flow out of the enclosure at the open top. The velocity and temperature distributions are also measured, in order to understand the basic nature of such flows. Several other effects, such as the entrainment into the flow, are also considered in this study.

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Section: _ -mentioning

confidence: 99%

Effect of opposing buoyancy on the flow in free and wall jets

Goldman

Jaluria

1986

J. Fluid Mech.

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“…Consideration of any other distribution merely requires the introduction of two constants for the dimensionless shape factors. Relating (1) and (2) identifies the physical scale of the source, r 0 = Q 0 /M 1/2 0 , as an alternative length scale that is sometimes used to scale experimental data [27] and that has been identified as the dominant scale for 'lazy' [5] as opposed to the relatively forced source conditions we consider herein. We note from (2) that the source scale can be expressed in terms of Fr 0 and the jet-length as…”

Section: Dimensional Considerationsmentioning

confidence: 99%

From free jets to clinging wall jets: The influence of a horizontal boundary on a horizontally forced buoyant jet

Burridge

Hunt

2017

Phys. Rev. Fluids

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We investigate the incompressible turbulent jet formed when buoyant fluid is steadily ejected horizontally from a circular source into an otherwise quiescent uniform environment. As our primary focus, we introduce a horizontal boundary beneath the source. For sufficiently small separations, the jet attaches and clings to the boundary, herein the 'clinging jet', before, further downstream, the jet is pulled away from the boundary by the buoyancy force. For larger sourceboundary separations, the buoyant jet is free to rise under the action of the buoyancy force, herein the 'free jet'. Based on measurements of saline jets in freshwater surroundings we deduce the conditions required for a jet to cling. We present a data set that spans a broad range of source conditions for the variation in volume flux (indicative of entrainment), jet perimeter and jet centreline for both 'clinging' and 'free' jets. For source Froude numbers Fr 0 ≥ 12 the data collapses when scaled, displaying universal behaviours for both clinging and free jets. Our results for the variation in the volume flux across horizontal planes, πQ jet , show that within a few jet-lengths of the source, πQ jet for the clinging jet exceeds that of a free jet with identical source conditions. However, when examined in a coordinate following the jet centreline πQ jet for free jets is greater.Finally, we propose a new parameterisation for an existing integral model which agrees well with our experimental data as well as with data from other studies. Our findings offer the potential to tailor the dilution of horizontal buoyant jets by altering the distance at which they are released from a boundary.

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“…The Environmental Protection Agency (EPA) funded many investigations in this area over a number of years. The experimental work that Professor Pletcher performed was partially used to verify the many computational investigations he performed with his students in the same area (see, for example, Madni and Pletcher [20,21]).…”

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confidence: 99%

In Memoriam: Professor Richard H. Pletcher (1935–2015), Who Advanced Computational Fluid Mechanics and Heat Transfer

Battaglia

Manglik

Sherif

2016

Journal of Fluids Engineering

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It is with great sadness that we share with you the loss of a dear colleague and friend, Dr. Richard H. Pletcher. He was one of the pioneers and an internationally renowned expert in computational fluid mechanics and heat transfer and was not only inspirational in directing the careers and lives of so many of us but also a mentor, who was extremely supportive and kind to all. Richard, or Dick, as we all personally and collegially addressed him, passed away on Saturday, Sept. 12, 2015, having been diagnosed with terminal cancer. His 80 years of life is marked with multifaceted contributions to engineering, as his work helped advance computational techniques to solve challenging problems in aerospace and mechanical engineering. Dick is remembered for his large body of work in heat transfer, fluid mechanics, buoyant jets and plumes, turbulence modeling, separated flows, viscous-inviscid interactions, computational fluid mechanics and heat transfer, and large-eddy simulation (LES) of complex turbulent flows. Richard was born in Elkhart, IN on May 21, 1935 to Raymond Harold Pletcher and Annabelle Mary Pletcher. He attended Purdue University and graduated with a Bachelor of Science in Mechanical Engineering in 1957. He married Carol Robbins on June 9, 1957 in Elkhart, and the couple soon thereafter moved to California so that he could report for active duty in the U.S. Navy. Dick proudly served as Ensign and Lieutenant (junior grade) for 3 years with amphibious forces in the Pacific. He served as an engineering officer of a landing craft utility division and assistant gunnery officer on a landing ship dock. After military service, Dick attended graduate school at the Cornell University where he received M.S. (1962) and Ph.D. (1967) degrees. During his doctoral studies, he was employed as an instructor by Cornell University for 3 years. He also worked as a senior research engineer in propulsion at the United Aircraft Research Laboratories in Hartford, CT (1965-1967), and subsequent to doctoral graduation, he joined the faculty in the Department of Mechanical Engineering at the Iowa State University (ISU), AMES, IA, in 1967. During Professor Pletcher's tenure at ISU, he left a legacy of affable collegiality, excellence in teaching, and path-breaking scholarship in computational modeling of complex fluid dynamics and heat transfer systems. His expertise centered on computational fluid dynamics (CFD), whereby he developed and taught courses for over 40 years in this new and emerging field. With Professor Dale Anderson and Professor John C. Tannehill in the Department of Aerospace Engineering at the ISU, a two-course sequence in computational fluid mechanics and heat transfer was developed in 1972. These courses were among the first in the U.S. in that specialty, which was born from the computer age. Papers based on numerical simulations carried out by Professor Pletcher appeared as early as 1965, a time when computer use for simulation in engineering was in an infant state. The early teaching activities in CFD were accompa...

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Buoyant Jets Discharging Nonvertically Into a Uniform, Quiescent Ambient—A Finite-Difference Analysis and Turbulence Modeling

Cited by 15 publications

References 0 publications

Effect of opposing buoyancy on the flow in free and wall jets

Effect of opposing buoyancy on the flow in free and wall jets

From free jets to clinging wall jets: The influence of a horizontal boundary on a horizontally forced buoyant jet

In Memoriam: Professor Richard H. Pletcher (1935–2015), Who Advanced Computational Fluid Mechanics and Heat Transfer

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