The Nonisothermal Pipe Flow (nipfl) interface (), found under the Nonisothermal Flow branch () when adding a physics interface, is used to compute the temperature, velocity, and pressure fields in pipes and channels of different shapes. It approximates the pipe flow profile by 1D assumptions in curve segments, or lines. These lines can be drawn in 2D or 3D and represent simplifications of hollow tubes. The physics interface is available in 3D on edges and 2D on boundaries.

When this physics interface is added, these default nodes are also added to the Model Builder — Fluid, Pipe Properties, Pressure, Temperature, and Initial Values. Then, from the Physics toolbar, add other nodes that implement, for example, boundary conditions and volume forces. You can also right-click Nonisothermal Pipe Flow to select physics features from the context menu.

The Label is the default physics interface name.

The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.

The default Name (for the first physics interface in the model) is nipfl.

Select a Fluid model — Newtonian (the default), Power law, or Bingham.