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Thermal and fingering convection in ...

Chen, Falin.

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Thermal and fingering convection in superposed fluid and porous layers.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Thermal and fingering convection in superposed fluid and porous layers./
Author:	Chen, Falin.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 1989,
Description:	145 p.
Notes:	Source: Dissertations Abstracts International, Volume: 51-06, Section: B.
Contained By:	Dissertations Abstracts International51-06B.
Subject:	Materials science. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9000768

Thermal and fingering convection in superposed fluid and porous layers.
Chen, Falin.

Thermal and fingering convection in superposed fluid and porous layers. - Ann Arbor : ProQuest Dissertations & Theses, 1989 - 145 p.

Source: Dissertations Abstracts International, Volume: 51-06, Section: B.

Thesis (Ph.D.)--The University of Arizona, 1989.

This item must not be sold to any third party vendors.

Thermal and fingering convection in a horizontal porous layer underlying a fluid layer was studied using linear stability analysis, experiment (for the thermal convection case only), and nonlinear simulation. For the thermal convection case, the linear analysis shows that when the fluid layer is thin, convection is largely confined to the porous layer. When the fluid layer thickness exceeds 15% of the porous layer thickness, convection is localized in the fluid layer and the critical wavelength is dramatically reduced. Experimental investigations were then conducted in a test box 24 cm x 12 cm x 4 cm high to substantiate the predictions. The ratio of the thickness of the fluid layer to that of the porous layer, d, varied from 0 to 1. The results were in good agreement with predictions. To investigate supercritical convection, a nonlinear computational study was carried out. It was found that for d $\\leq$ 0.13, the Nusselt number increases sharply with the thermal Rayleigh number, whereas at larger values of d, the increase is more moderate. Heat transfer rates predicted for d = 0.1 and 0.2 are in good agreement with the experimental results. For salt-finger convection at R$\\sb{\\rm m}$ $\\leq$ 1, the critical value of the solute Rayleigh number R$\\sb{\\rm sm}$ decreases as d increases; the convection is unicellular. For 5 $\\leq$ R$\\sb{\\rm m}$ $\\leq$ 10, the critical R$\\sb{\\rm sm}$ initially decreases with d, and then remains almost constant for larger values of d; multicellular convection prevails at high d. For 20 $\\leq$ R$\\sb{\\rm m}$ $\\leq$ 50, the critical R$\\sb{\\rm sm}$ first decreases and then increases as d increases from 0 to 0.1. When d $>$ 0.1, the critical R$\\sb{\\rm sm}$ decreases slowly with d and remains almost constant for d $\\geq$ 0.4. In the nonlinear computations for R$\\sb{\\rm m}$ = 1, periodic convection sets in at a value of R$\\sb{\\rm sm}$ between ten and eleven times the critical value. For the case of R$\\sb{\\rm m}$ = 50, an aperiodic oscillation occurs when R$\\sb{\\rm sm}$ is between four and five times the critical value. For the superposed layer cases d = 1 and 0.5, the convection characteristics are similar to those of thermal convection when R$\\sb{\\rm m}$ = 0.01. For R$\\sb{\\rm m}$ = 1, it was found that the onset of salt-finger convection is oscillatory. For R$\\sb{\\rm m}$ = 50, the nonlinear code failed to obtain satisfactory results.Subjects--Topical Terms:

543314
Materials science.

Thermal and fingering convection in superposed fluid and porous layers.
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035 $a (MiAaPQ)AAI9000768
035 $a AAI9000768
040 $a MiAaPQ $c MiAaPQ
100 1 $a Chen, Falin. $3 3434412
245 1 0 $a Thermal and fingering convection in superposed fluid and porous layers.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 1989
300 $a 145 p.
500 $a Source: Dissertations Abstracts International, Volume: 51-06, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Chen, C. F.
502 $a Thesis (Ph.D.)--The University of Arizona, 1989.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a Thermal and fingering convection in a horizontal porous layer underlying a fluid layer was studied using linear stability analysis, experiment (for the thermal convection case only), and nonlinear simulation. For the thermal convection case, the linear analysis shows that when the fluid layer is thin, convection is largely confined to the porous layer. When the fluid layer thickness exceeds 15% of the porous layer thickness, convection is localized in the fluid layer and the critical wavelength is dramatically reduced. Experimental investigations were then conducted in a test box 24 cm x 12 cm x 4 cm high to substantiate the predictions. The ratio of the thickness of the fluid layer to that of the porous layer, d, varied from 0 to 1. The results were in good agreement with predictions. To investigate supercritical convection, a nonlinear computational study was carried out. It was found that for d $\\leq$ 0.13, the Nusselt number increases sharply with the thermal Rayleigh number, whereas at larger values of d, the increase is more moderate. Heat transfer rates predicted for d = 0.1 and 0.2 are in good agreement with the experimental results. For salt-finger convection at R$\\sb{\\rm m}$ $\\leq$ 1, the critical value of the solute Rayleigh number R$\\sb{\\rm sm}$ decreases as d increases; the convection is unicellular. For 5 $\\leq$ R$\\sb{\\rm m}$ $\\leq$ 10, the critical R$\\sb{\\rm sm}$ initially decreases with d, and then remains almost constant for larger values of d; multicellular convection prevails at high d. For 20 $\\leq$ R$\\sb{\\rm m}$ $\\leq$ 50, the critical R$\\sb{\\rm sm}$ first decreases and then increases as d increases from 0 to 0.1. When d $>$ 0.1, the critical R$\\sb{\\rm sm}$ decreases slowly with d and remains almost constant for d $\\geq$ 0.4. In the nonlinear computations for R$\\sb{\\rm m}$ = 1, periodic convection sets in at a value of R$\\sb{\\rm sm}$ between ten and eleven times the critical value. For the case of R$\\sb{\\rm m}$ = 50, an aperiodic oscillation occurs when R$\\sb{\\rm sm}$ is between four and five times the critical value. For the superposed layer cases d = 1 and 0.5, the convection characteristics are similar to those of thermal convection when R$\\sb{\\rm m}$ = 0.01. For R$\\sb{\\rm m}$ = 1, it was found that the onset of salt-finger convection is oscillatory. For R$\\sb{\\rm m}$ = 50, the nonlinear code failed to obtain satisfactory results.
590 $a School code: 0009.
650 4 $a Materials science. $3 543314
650 4 $a Mechanical engineering. $3 649730
650 4 $a Metallurgy. $3 535414
690 $a 0794
690 $a 0548
690 $a 0743
710 2 $a The University of Arizona. $3 1017508
773 0 $t Dissertations Abstracts International $g 51-06B.
790 $a 0009
791 $a Ph.D.
792 $a 1989
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9000768