Domains and Boundary Conditions

Domains

Domains are regions of space in which the equations of fluid flow or heat transfer are solved

Only the mesh components which are included in a domain are included in the simulation

How to Create a Domain (as shown earlier)

Define Domain Properties

-Right-click on the domain and pick Edit

-Or right-click on Flow Analysis 1 to insert a new domain

Domain Creation

-General Options panel: Basic Settings

Location: Only assemblies and 3D primitives

-Domain Type: Fluid, Solid, or Porous

-Coordinate Frame: select coordinate frame from which all domain inputs will be referenced to

Not to be confused with the reference frame, which can be stationary or rotating

The default Coord 0 frame is usually used

-Fluids and Particles Definitions: select the participating materials

Domain Creation–Reference Pressure

Domain Creation - Buoyancy

Full Buoyancy Model

-Evaluates the density differences directly

-Used when modeling ideal gases, real fluids, or multicomponent fluids

-A Reference Density is required

Use an approximate value of the expected domain density

Buoyancy Ref. Density

-The Buoyancy Reference Density is used to avoid round-off errors by solving at an offset level

-The Reference Pressure is used to offset the operating pressure of the domain, while the Buoyancy Reference Density should be used to offset the hydrostatic pressure in the domain

The pressure solution is relative to rref g h, where h is relative to the Reference Location

If rref = the fluid density (r), then the solution becomes relative to the hydrostatic pressure, so when visualizing Pressure you only see the pressure that is driving the flow

-Absolute Pressure always includes both the hydrostatic and reference pressures

-For a non-buoyant flow a hydrostatic pressure does not exist

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