There are a number of details views in CFX-Pre that require the entry of physical quantities. For example, when you set the physical properties for a fluid, or enter values for boundary conditions, the units in which you input the data must be selected.
A list of possible units for the quantity of interest is provided, but you may want to use an expression for the quantity, in which case you must specify the units. You can use any units that are consistent with the quantity you are describing. The default units in CFX-Pre are SI.
The units selector is automatically filled in using the default units for the quantity. You can select other commonly used units for that quantity from the drop-down list in the units selector.