Publication de 4 numéros par an
ISSN Imprimer: 1065-3090
ISSN En ligne: 1940-4336
Indexed in
DO THE INTRUSIVE PROBES ALTER THE CHARACTERISTIC LENGTH-SCALES OF NATURAL CONVECTION?
RÉSUMÉ
Initiation and development of natural convection patterns such as cylindrical rolls and hexagonal cells depend on the system length-scales and external surroundings. In this work, the influence of inserted thermocouple probes on buoyant flow fields during bottom cooled solidification is investigated, wherein the convective and anomalous region of 0-4°C in water evolves continuously by forming different recirculation patterns. The experiments, performed with the use of the Mach−Zehnder interferometer and particle image velocimetry (PIV) techniques for obtaining full-field temperature and flow fields, respectively, compare and contrast the thermal field and flow patterns in the presence and absence of inserted thermocouple probes. The temperature field measurements show that the presence of thermocouples, even though located close to the side walls, delayed the initiation of convection, whereas the flow characteristics clearly indicated a considerable change in the magnitude of velocities and their circulating patterns. The patterns indicated a distinct behavior of forming more stable hexagonal cells when the probes did not intrude into the convecting region. The Rayleigh−Benard linear stability analysis confirmed that the length-scale available for recirculation was modified by the presence of thermocouple probes. These observations were further corroborated with the help of PIV experimental images obtained from multiple projections. The study clearly emphasized the importance of nonintrusive measurements, and how assessments of critical Rayleigh numbers for buoyant flows can be deceiving when inserted probes are present.
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Monde Aniket D., Chawla Oaj, Kumar Virkeshwar, Karagadde Shyamprasad, Chakraborty Prodyut R., Shrinkage induced flow during directional solidification of pure substance in a bottom cooled cavity: A study on flow reversal phenomena, Physics of Fluids, 32, 4, 2020. Crossref
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Kumar Virkeshwar, Abhishek G. S., Srivastava Atul, Karagadde Shyamprasad, On the mechanism responsible for unconventional thermal behaviour during freezing, Journal of Fluid Mechanics, 903, 2020. Crossref
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Jha Ajit Kumar, Shukla Prashant, Ghosh Pradyumna, Free convection boundary layer correlations for a vertical plate with nonuniform heating, Numerical Heat Transfer, Part B: Fundamentals, 2022. Crossref
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Jha A.K., Shukla P., Khisti Pranav M, Ghosh Pradyumna, Yadav S.K., Investigation of onset of velocity transition in free convection over an inclined flat plate by PIV, Experimental Thermal and Fluid Science, 140, 2023. Crossref
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Jha Ajit Kumar, Shukla P. , Ghosh P. , Khisti Pranav , Dubey Abhinav , VISUALIZATION AND MEASUREMENT OF NATURAL CONVECTION BOUNDARY LAYER BY PARTICLE IMAGE VELOCIMETRY , Journal of Flow Visualization and Image Processing, 30, 2, 2023. Crossref