Single phase models, as the name suggests, are simulations involving a single base fluid with Newtonian or non-Newtonian rheology. Common applications include pipe flow simulations, well-baffled agitated tanks, jet mixing systems, and pumps. Within this configuration, users must specify the fluid density and define the constitutive relationship between fluid stress and fluid strain. As discussed in particleFields additional phases (such as discrete bubbles and discrete solid particle) can be added to the system and one- or two-way coupled to the fluid. Secondary miscible fluids with arbitrary densities and viscosities, as discussed in Miscible Fluids, can be also added to the base fluid. Thermal fields and scalar fields can also be superimposed on the single phase fluid, as discussed in Basic Concepts and Scalar Fields.
Within the single phase model, users can chose from one of five constitutive relationships:
Power law (with or without a yield stress)
Briefly speaking, relationships (1)-(3) are familiar Newtonian and non-Newtonian rheology models. Relationship (4) represent custom expressions that may be more complex functions of strain, stress, age, species concentration, miscible fluid volume fraction, custom variables, particle concentration, and temperature. Additional details for each of these relationships are provided in Fluid Rheology
In single phase models, the entire interior zone of the lattice domain is assumed to be filled with the fluid.