Preliminary Considerations on Double Diffusion Instabilities in Two Quaternary Isothermal Systems of Biological Relevance

Double diffusion phenomena plays a significant role in the transport of species when two or more driving forces are involved in the generation of buoyancy. This is the case of simultaneous gradients of temperature and concentration or concentration gradients of two or more species in multicomponent liquid mixtures. Double diffusion phenomena can be presented in different forms, which are mostly referred as fingers and overstability. The aim of this work was to establish limiting initial conditions for certain mixtures in order to control appearance of dissipative structures such as fingers and overstability in quaternary mixtures by simplifying these systems into ternary subsystem. Limits were applied for quaternary mixture of biological reference. Limits are established using analytical solution and confirmed by numerical simulations conducted in open source package OpenFOAM. Graphs of stability are obtained for certain mixtures from analytical solution along with procedure how to obtain them. quaternary mixtures region where both instabilities are presented simultaneously is found. This behaviour is not possible for ternary mixtures.