Surface tension-driven phenomena are ubiquitous in nature and in many industrial applications. As with technological advancement, the transport process often involves complex fluids, such as colloidal dispersions or nanofluids, polymer liquids, and two-phase systems. Nanofluids represent colloidal dispersions made of a mixture of a base fluid and nanoparticles of diameter d_p^* between 10 and 100 nm.
We investigate the onset of thermosolutal instabilities in a moderately dense quiescent nanofluid layer with a deformable interface in the presence of a gravity field and the Soret effect. The onset of various instabilities is investigated for cases of both cooling and heating at the solid substrate. We find the emergence of monotonic solutocapillary instability in the case of cooling at the substrate, where the disturbance minima exhibit competition with variation in the gravity field and the Soret effect.
