Swaying motion in thermal plume above a horizontal line heat source

Noto, Katsuhisa

doi:10.2514/3.28768

Cited by 28 publications

(23 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The present FFT computation is therefore accurate. Furthermore, the plume frequency distribution at unstratified condition obtained by the present spectrum 770 K. NOTO AND S. MITSUHASHI analysis agreed well with the previous result [13,14]. That is, the present FFT computation is valid.…”

Section: Spectrumsupporting

confidence: 90%

Buoyant Flow Characteristics With Thermal Cylinders in Stably Stratified Air

Noto

Mitsuhashi

2005

Numerical Heat Transfer, Part A: Applications

View full text Add to dashboard Cite

A flow induced by thermal cylinders at neutral (st ¼ 0) or stable (0 < st) stratification, where st is the stratification degree, is analyzed numerically. As a result, a new kind of flow resulting from thermal cylinders is discovered, and agrees well with the previous experimental result of flow visualization as follows: At 0 st, the thermal cylinder flow (TCF) is defined as the flow due to a thermal cylinder, and is generated intermittently. A TCF rises and develops to a small roof-shape flow, which separates to the right and left directions near the thermal flow front. Then, at st ¼ 0 and a small st, one edge of a layer is fixed near the midplane, and another edge of a layer moves outward. Thus a nonsliptype layer is formed. Furthermore, because many thermal cylinders arrive intermittently at the front, many layers of nonslip type are formed. On the other hand, at a large st, all the layers slip off the midplane, and move slowly outward. As a result, many layers of slip type are formed.

show abstract

Section: Spectrumsupporting

confidence: 90%

Buoyant Flow Characteristics With Thermal Cylinders in Stably Stratified Air

Noto

Mitsuhashi

2005

Numerical Heat Transfer, Part A: Applications

View full text Add to dashboard Cite

show abstract

“…These mechanisms depend on the ratio of depth of immersion to vessel width. The oscillation frequency f = 0.0657Ra 0.433 (0.310 6 < Ra < 810 6 ) [28] as per earlier results [27]. For a pair of cylinders, Eckert and Soehngen [29] found that the induced temperature and velocity fields due to the buoyant plume from downstream cylinders have opposing effects.…”

Section: Case I: Forced Convection Heat Transfer To An Impinging Syntsupporting

confidence: 71%

“…At high Rayleigh number (Ra > 10 10 ), the plume transitions to the turbulent regime [24]. A greater body of research is available on swaying plumes from thin horizontal wires, regarded as line heat sources [25,26,27]. Desrayaud and Lauriat [28] investigated buoyancy induced flow from a horizontal wire heat source; for rectangular vessels two destabilizing mechanisms lead to low frequency motion due to instability of the buoyant plume.…”

Section: Case I: Forced Convection Heat Transfer To An Impinging Syntmentioning

confidence: 99%

High Dynamic Range Particle Image Velocimetry Applied to Heat Convection Studies

Persoons

2014

EPJ Web of Conferences

View full text Add to dashboard Cite

Abstract. Convective heat transfer occurs in a wide range of engineering applications, from nuclear reactors to portable electronic devices. Accurate whole-field turbulence and flow measurements are crucial to understanding convective heat transfer in complex flow fields, thereby enabling optimal design of these devices. Particle image velocimetry (PIV) is the preferred whole-field flow measurement technique. However in many configurations the dynamic velocity range of conventional PIV is too limited to accurately resolve both high mean velocities and turbulence intensities in lower velocity regions. This paper employs high dynamic range (HDR) PIV with an advanced acquisition and processing technique based on multiple pulse separation (MPS) double-frame imaging. The methodology uses a conventional adaptive multi-grid algorithm for vector evaluation, and determines the optimal pulse separation in space and time in a post-processing routine. Two test cases are discussed: For an impinging synthetic jet flow (Case I), HDR PIV increases the dynamic velocity range 25-fold compared to conventional PIV. For an oscillatory buoyant plume from a pair of horizontal heated cylinders (Case II), the dynamic velocity range is increased 5.5 times. This technique has yielded new insights in synthetic jet heat transfer by correlating local surface heat transfer rates to near-wall turbulence intensity in a single whole-field measurement.

show abstract

“…Neutral stability curves were obtained in terms of the Grashof number. Noto [2] performed experimentally the sway spectrum, the sway frequency and several characteristics in the sway motion of a laminar thermal plume of air arising from a horizontal line source. Srinivasan and Angrirasa [3] presented a numerical study of laminar axisymmetric plumes that emanate from a source of combined buoyancy due to simultaneous heat and mass diffusion.…”

Section: Introductionmentioning

confidence: 99%