A program system applied to modeling physicochemical processes in forming chemical fibers

A visual modeling system has been developed in which the mathematical models for molding are represented as sets of linked physicochemical phenomena. If the molding is supported by input data, the model enables one to determine new technological parameters when there is a change in the range of fibers or there are changes in some of the technological parameters. The models represent a program for setting up new processes for forming chemical fibers, in which one states a set of necessary data providing viability and filling the model database. These models can be used in devising systems for automating chemical fiber shaping. The technology for making chemical fibers from polymer melts and solutions runs ahead of developments in polymer science (including polymer chemistry, physical chemistry, and physics) [1]. Consequently, attempts have been made and are still being made to construct an adequate model for the most important process in this technology: fiber molding. Such models can be used to design new processes and optimize existing ones when there are changes in the range of fibers and when it is necessary to select empirically the technological parameters to use with industrial plant. This allows one to change the working conditions and minimize expensive experiments. An adequate model to a considerable degree organizes and cheapens the predesign stage in research and calculation. It amounts to completing the database for the model with a set of experimental data obtained in laboratories. To handle these tasks, we have set up a package of models for fiber formation from polymer melts and solutions, which incorporate the basic physicochemical processes, i.e., a technological process is represented as a set of linked physicochemical phenomena, each of which is reflected by an equation or function in the model. To simulate molding, we propose an approach in which one examines the physicochemical phenomena in stretching a jet of polymer solution or melt involving reduction in the general equations. This provides equation systems for numerical analysis of those phenomena that are most accessible to analysis or solution, while also more fully reflecting the actual experimental data. One can implement and use these models for chemical fiber formation only in a program system for various reasons. Firstly, the processes are described by nonlinear equations with mobile boundaries, which means that only numerical solution is possible. Secondly, certain problems can be resolved in using the models and the set of unified software modules by linking them into a system. Thirdly, it is necessary to use databases for describing the various forms of formation, elements in the technological process schemes, the properties of polymer solutions and melts, and so on. The purposes of this article are to describe the program system for simulating the stages in chemical fiber formation and also the methods and algorithms used in it. The system provides for simulating the following processes on the basis of models: classical and aerodynamic molding from polymer melts and also dry and wet molding from polymer solutions. For wet formation, we consider various forms of gel formation: diffusional, thermotropic, and mechanotropic. Each of these methods is described below. Forming from melt model: this is based on a one-dimensional equation of motion derived from the balance of forces acting on a jet in steady-state motion [2, 3], or else by radial averaging from the Navier-Stokes equation and the edge conditions, as in [4], and from the one-dimensional or two-dimensional equations for heat transfer from the fiber and air. The