Pw. Shipp et al., EFFECT OF THERMAL RAYLEIGH AND LEWIS NUMBERS ON DOUBLE-DIFFUSIVE NATURAL-CONVECTION IN A CLOSED ANNULUS, Numerical heat transfer. Part A, Applications, 24(4), 1993, pp. 451-465
A numerical study for steady laminar double-diffusive natural convecti
on within a vertical closed circular annuus is examined with a constan
t temperature and mass species (concentration) difference imposed acro
ss the vertical walls. The effects of thermal Rayleigh number (5000 le
ss-than-or-equal-to Ra(T) less-than-or-equal-to 100,000) and Lewis num
ber (1 less-than-or-equal-to Le less-than-or-equal-to 10) are investig
ated for buoyancy ratios of -2, -1.2, -1, and 2, representing conditio
ns for mass species dominated opposing, transitional, thermal dominate
d opposing, and mass species dominated aiding flows, respectively. The
relationships between the thermal Rayleigh number and the average Nus
selt and Sherwood numbers for -10 less-than-or-equal-to n less-than-or
-equal-to 10 have been obtained for a Lewis number of 5. Also, the rel
ationship between the Lewis number and the average Nusselt and Sherwoo
d numbers for the same buoyancy ratio range have been obtained for a c
onstant thermal Rayleigh number of 50,000. The Lewis and thermal Rayle
igh numbers are found to influence the buoyancy ratios at which flow t
ransition and flow reversal occur.