  The effects of the semitransparent winodw's aspect ratio on the interaction
of the collimated beam with natural convection have been investigated
numerically in the present work. The combination of geometrical parameters of
the semitransparent window, i.e., height ratio ($h_r$) and window width ratio
($w_r$) and Planck numbers of the medium have been considered. The other
parameters, like flow parameter (Ra$=10^5$), fluid parameter (Pr=0.71), thermal
parameter (N), Irradiation (G=1000 $W/m^2$), Angle of incidence ($\phi=135^0$)
and geometrical parameter of the geometry ($A_r$=1) and the wall conditions
have been kept constant. A collimated beam is irradiated with irradiation value
(G=1000 $W/m^2$) on the semitransparent window at an azimuthal angle ($\phi)
135^0$. The cavity is convectively heated from the bottom with heat transfer
coefficient 50 $W/m^2 K$ and free stream temperature 305 $K$. A semitransparent
window is created on the left wall and isothermal conditions (T=296 $K$) is
applied on the semitransparent, left and right vertical walls, wherein
adiabatic conditions are applied on upper wall of the cavity. The dynamics of
two vortices inside the cavity change considerably by combinations these
semitransparent window's aspect ratio and Planck number (Pl) of the medium. The
left vortex breaks into two parts and remains confined in upper and lower left
corners for some combination of aspect ratios and Planck numbers of the medium.
The thermal plume flickers depending on the situation of dynamics of two
vortices inside the cavity. The localized hating of the fluid happens mostly
for large height ratio of semitransparent window. The conduction; radiation and
total Nusselt number are also greatly affected by the semitransparent window's
aspect ratio and the Planck number of the medium.
