Dynamics of megasystems in geochemistry: Formation of base models of processes and simulation algorithms

On the basis of thermodynamic-potential minimization, an approach to constr uction and investigation of simulation models of dynamic megasystems has be en developed. Dynamic megasystems are chemically interacting natural and ge otechnical systems (reservoirs) connected with each other by direct, revers e, and through flows of matter and energy. The structure of a simulation model is formed by combining basic constituen ts and directive parameters. Systems and connecting flows may be aggregated into a single physicochemical object - a megasystem - in different ways. The evolution of megasystems can be calculated by two algorithms. In the fi rst algorithm, two operations are performed in time unit: calculation of si multaneous equilibria in all systems and transfer of matter with flows in a ccordance with the specified matrix of macrokinetic coefficients of transfe r. In the second algorithm, the evolution of megasystems in time and space proceeds in cycles. In each cycle, equilibrium calculation and matter trans fer are performed consecutively from system to system in accordance with th e system numbering and matrix of macrokinetic coefficients. The number of t ime units is equal to the number of the systems of a megasystem. The cycle of the latter algorithm ends in the system with the greatest number, and th e next cycle begins in the first system. The most important peculiarity of both the algorithms is separation and division of flows into groups of mobi le phases. Flows of aqueous solutions, gas mixture, solid substances (such as aeolian dust, furnace charge, mineral suspension in water), liquid hydro carbons, organic matter, etc, can be transferred from system to system. Eac h group of mobile phases has a matrix of macrokinetic coefficients. If requ ired, macrokinetic coefficients can be recalculated by built-in algorithmic operators in the intervals between time units. The proposed approach is illustrated by two examples. In the first one, the resistance of Lake Imandra (north of the Kola Peninsula) to pollution with nepheline-apatite production waste was investigated by an integral physico chemical index - pH of water, depending an the waste volume. In the second example, matter redistribution in the Al2O3-SiO2-H2O megasystem was studied , This redistribution is caused by an external energetic effect formation o f a stationary nonisothermal profile at T = 300-440 degrees C and P = 3 kba r. The simulation results are compared with Vidal's experimental data. The formation procedures and simulation algorithms for dynamic megasystems were realized in the form of the <<Reservoir dynamics>> module included int o the program complex Selektor-S designed in 1997. It may be used for solvi ng different scientific problems as well as in engineering and educational institutions.