The Viscoelastic Flow (vef) interface () is used for simulating single-phase flows of viscoelastic fluids. The physics interface is only suitable for incompressible flows.

The Viscoelastic Flow interface is available for stationary and time-dependent analyses. The main feature is Fluid Properties, which adds the Navier–Stokes equations, continuity equations, and the constitutive relations between the extra elastic stress term and the velocity gradient. The Fluid Properties feature provides an interface for defining the fluid material and its properties. Viscoelastic, Newtonian, and Inelastic non-Newtonian constitutive relations are available. The boundary conditions are essentially the same as for the Laminar Flow interface. When this physics interface is added, the following default nodes are also added in the Model Builder:

Then, from the Physics toolbar, add other nodes that implement, for example, boundary conditions and volume forces. You can also right-click Viscoelastic 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 vef.

When the Include gravity check box is selected, a global Gravity feature is shown in the interface model tree.

Also, when the Include gravity check box is selected, the Use reduced pressure option changes the pressure formulation from using the total pressure (default) to using the reduced pressure. For more information, see Gravity.

If the Viscoelastic constitutive relation is selected, the Fluid Properties node also adds as variables the components of the elastic stress tensor.

For all other settings, see The Laminar Flow Interface.