Competition of overstability and stabilizing effects in viscoelastic thermovibrational flow

Attention is paid to a specific form of thermal convection which encompasses viscoelastic and thermovibrational effects in a single problem or framework. The main objective is understanding the relationship between the phenomenon of overstability and periodic forcing through numerical solution of the governing equations in their complete, time-dependent, and nonlinear form. Fluid motion is found for values of the control parameter one order of magnitude smaller than the threshold to be exceeded in the equivalent Newtonian case. When the disturbances saturate their amplitude, patterns emerge that are reminiscent of the superlattice structures typical of complex order. In the present case, such peculiar modes of convection are driven by the coexistence of two distinct spatial scales, each displaying a different temporal dependence, driven by the interplay of the time-varying (stabilizing or destabilizing) acceleration induced by vibrations and the ability of the fluid to store and release elastic energy.

Automated summary

The study focuses on a specific form of thermal convection, which includes viscoelastic and thermovibrational effects, in order to understand the relationship between overstability and periodic forcing through numerical solutions of the governing equations. Fluid motion is observed for control parameter values one order of magnitude smaller than the threshold, and patterns resembling superlattice structures emerge when disturbances saturate. These peculiar convection modes are driven by the coexistence of two distinct spatial scales with different temporal dependences.