Figure 4From: Thermal instability in a non-Darcy porous medium saturated with a nanofluid and with a convective boundary condition Influence of the Biot number on (a) ( Ra s ) crit and (b) ( Ra osc ) crit as a function of Da with Va=0.3 , Rn=−3 , M=2 , N B =10 , Le=500 , N A =5 , σ=3 , ε=0.7 . Back to article page