ABSTRACT
After being cut from the field, vegetal material processed by a combine harvester evolves from its initial nonhomogenous, fibrous structure to unbound, multicomponent mixtures, which segregate and separate in different processing zones of the machine, following in series or parallel paths, in as many component flows. Cut material is formed of bendable/ fragile straws/stalks with ears, panicles, and so forth. Multicomponent mixtures of vegetal material consist of dynamically deformed or fragmented straw pieces, chaff, leaves, unthreshed ears, and grains of base crop, as well as weed plants and seeds, or even nonbiologic objects (e.g., soil granules). Characteristic of such flows of multicomponent materials is an uncertainty in the location and time of the particular constituents. Practically, it is not possible to exactly measure or predict the evolution of such component mixtures due to individual, unbound components of specific behavior, the complexity of component interactions, nonhomogeneity, and discontinuities of the mixture flow, as well as physical or simulation scaling. Besides, these components are not integrated within a fluid with relative predictable behavior-not to mention that high values of moisture released by vegetal material due to mechanical compression create additional disturbances by component adherence to active or passive elements of combine working units. As a consequence, a stochastic approach or an ensemble averaging concept may be used.
