Figure 1

The case of rigid upper and lower walls, Rb = 0 (no microorganisms): (a) Oscillatory and non-oscillatory instability boundaries in the (Ra_c, Rn) plane. (b) Critical wavenumber in the (Ra_c, Rn) plane. (c) Square of the oscillation frequency, ω², versus the nanoparticle concentration Rayleigh number (for oscillatory instability to occur, ω² must be positive so that ω remains real).