Create: Fundamentals

Fundamental objects include static geometry and moving geometry, as well as inlets and outlets in your system. These objects typically define object motion within the system and where boundary conditions are applied.

Both static and moving bodies are characterized by a parent-child relationship. Within this relationship, the parent defines the global properties and boundary conditions assigned to a set of children. The parents have no topology or physical form until they are expressed through children geometry. The children define the shape, geometry, and topology of the solid surface, with the boundary conditions defined by the parent.

Static inlets and outlets have no child geometry and are defined using the edge or surface of an existing static body. Moving inlets and outlets likewise have no child geometry and are instead parameterized entirely by the parent.

Static and Moving Bodies

  • Static Body: Static bodies are fixed, non-deformable geometries that act as walls for fluids, particles, bubbles, and/or species. Examples of static bodies include vessel walls, internal coils, and baffles.

  • Moving Body: Moving bodies are geometries defined as moving surfaces in the model. They add momentum to your system. Examples of moving bodies include impellers, plunging objects, and rotating screws.

Boundary Conditions

  • Static Inlet/Outlet: Fixed inlets and oulets are sources and sinks of fluid. The fluid entering the system through an inlet can contain user-defined species concentrations, solid and bubble volume fractions, or user-defined temperature. Examples of fixed inlets and outlets include openings in a pipe, fluid nozzles, recirculation loops, and drains. Inlets and outlets must be backed by a solid boundary.

  • Moving Inlet/Outlet: Moving inlets and outlets define boundary conditions that translate and rotate over the course of a simulation. Examples of moving inlets and outlets include vial filling nozzles and spraying systems.

Variables and Reactions

  • Moving Body Variables: Moving body variables are quantities defined directly on the surfaces of moving meshes and are computed on the triangular mesh elements themselves.

  • Static Body Variables: Static body variables are quantities defined along solid surfaces that characterize interactions between walls, fluid, and particles. These variables are computed on voxels adjacent to the surface and projected onto the geometry for visualization.

  • Static Body Reactions: Static body reactions represent chemical reactions applied along solid surfaces, operating on scalar fields in voxels adjacent to the boundary. These reactions can depend on local fluid properties, species concentrations, particle behavior, and global variables, and may include heat effects when a thermal field is active.