The Lower Limit node () makes it possible to impose restrictions on degrees of freedom (field variables). These restrictions are checked after each substep of a segregated approach. The restriction is performed without any regards to the equations, so use this restriction with care. Enforcing a lower limit on a field variable can be useful to ensure positivity of a volume fraction of particles or the positivity of turbulence model variables, for example. Right-click a Segregated node to add a Lower Limit node.

By default, no variables have active lower limits. To activate lower limits for field variables, use the Lower limits (field variable) field to specify the variables and their scalar lower limits as space-separated pairs: field_variable_1 limit_value_1 field_variable_2 limit_value_2, and so on. For example, to impose a lower limit of 0.25 for the value of a field u in Component 1, enter comp1.u 0.25.