Solidification in the Presence of Natural Convection in a Hele-Shaw Cell - Selected Topics of Computational and Experimental Fluid Mechanics - page 367

Fig. 7 Red trace Kinetic energy of the flow L 2 as a function of time. Blue trace Velocity of the
solidification front

becomes stagnant at t 15.7 min. The velocity of the solidification front is also

shown in Fig. 7 to emphasize the different time scales of liquid and solid motions.

=

4 Discussion and Conclusions

Solidification in the presence of natural convection has been observed in a quasi two
dimensional system composed by water with spherical particles in suspension con-
fined to a Hele-Shaw cell. The experimental arrangement permits a full visualization
of the process both in the solid and the liquid regions. In the present experimen-
tal set up, the temperature boundary conditions on the upper and lower horizontal
walls are time dependent, but it is expected that the qualitative features of the results
observed are similar to those obtained in the time independent case. Our observations
indicate that the reduction of the region occupied by the liquid impacts greatly on
the convective pattern, but the shape of the solidification front is not much affected
by the convective motion. The presence of particle tracers may arguably modify the
dynamics of the solidification as compared with the a pure liquid (Peppin et al. 2007 );
however, it is likely that this effect has its largest impact at a microscopic level and
not on the macroscopic scale which is the main objective of the present report.

Acknowledgments Guillermo Ramírez acknowledges support from CONACYT-Mexico through
MSc. and PhD. grants. Mr. Agustín Barrera built an early version of the convective cell.