Engineering Units

Simcenter STAR-CCM+ has flexible and customizable support for engineering units. The standard SI and USCS systems are built in, and you can add new units as desired. Physical quantities can be specified and displayed in any of these units. Individual quantities can be specified with new units on the fly by simply typing something like “80 mph”.

A unit is a reference amount of a physical quantity used to measure quantities of the same dimensions. Each unit is represented by a node under Tools > Units.

A unit has an associated set of dimensions. For example, a meter has dimensions of length. A foot, inch, and millimeter also have dimensions of length. Any quantity with dimensions of length can therefore be expressed in meters, feet, inches, and millimeters.

The fundamental dimensions used in Simcenter STAR-CCM+ are:

  • Length
  • Time
  • Current
  • Mass
  • Temperature
  • Luminosity
  • Quantity
  • Angle

and the derived dimensions are:

  • Force
  • Energy
  • Power
  • Pressure
  • Velocity
  • Angular velocity
  • Volume
  • Moment
  • Stress

Every physical quantity has a set of dimensions which are one of these dimensions, or a combination of these basic dimensions. For example gravity has dimensions of acceleration, which is dimensions of length per time squared.

The technique for setting up a derived unit in a macro (corresponding to the Dimensions property of a scalar or vector quantity in the UI) was simplified in Simcenter STAR-CCM+ 2019.1. For details, see Scalar and Vector Quantities: Simpler Technique for Derived Units.