Bottom boundary layer in the Black Sea: formation of the stationary state

Abstract

We make an attempt to answer the following question: how a natural stationary system formed by a layer and an interface “selects” a unique set of governing parameters from a great number of possible collections under the conditions of double-diffusion layer convection (e.g., for the bottom boundary layer in the Black Sea)? As the “rule of selection,” we use the principle of minimum entropy production for systems close to the state of thermodynamic equilibrium. In the process of solution of the problem, the system is regarded as a heat engine. The proposed approach is reduced to a simple procedure of application of the principle of minimum entropy production to the analyzed case. The combined analysis of the theoretical results, the data of deepwater field measurements in the Black Sea, and the results of laboratory experiments leads us to the conclusion that, most likely, the stationary system “selects” its governing parameters according to the Prigogine–Glansdorff principle. The density ratio (approximately equal to three for the stationary case) proves to be the key parameter of the system.