EFFECTS OF ASYMMETRIC TEMPERATURE PROFILES ON THERMAL-CONVECTION DURING PHYSICAL VAPOR TRANSPORT OF HG2CL2

Asymmetric horizontal thermal profiles can change the flow field struc ture in the physical vapor transport (PVT) of Hg2Cl2. It is found that for the ratios of horizontal to vertical thermal Rayleigh numbers Ra- H/Ra greater than or equal to 1.5, the convetive flow structure change s from multicellular to unicellular for the base parametric state of R a = 2.79 x 10(4), Pr = 0.91, Le = 1.01, Pe = 4.60, Ar = 0.2 and C-s = 1.01. The unicellular flow structure obtained by increasing Delta T-H (Ra-H) is not likely to support the conjecture of the presence of unic ellular convective mode in the laser Doppler velocimetry (LDV) experim ents for PVT process of Hg2Cl2 (Kim et al., 1996). When the six parame ters of Ra, PI, Le, Pe, Ar and C, are fixed, the dimensional maximum m agnitude of the velocity vector \U\(max) is proportional to root Delta T-H.