Coordinate Systems

Simcenter STAR-CCM+ In-cylinder uses several coordinate systems for creating geometries, for defining the motion of the piston and the valves, for setting up the injector, or for postprocessing.

The following coordinate systems are available:


Coordinate System	Side View	Top View
Laboratory For the origin and the axis directions of this coordinate system, see Geometry Requirements.
Adjusted exhaust-valve [n] Coordinate System X Axis Direction, Y Axis Direction: see Calculation of X Axis and Y Axis Directions Z Axis Direction: aligned with valve stem axis, pointing towards piston Origin: centered on bottom of Head surface Reference System: Laboratory
Adjusted intake-valve [n] Coordinate System X Axis Direction, Y Axis Direction: see Calculation of X Axis and Y Axis Directions Z Axis Direction: aligned with valve stem axis, pointing towards piston Origin: centered on bottom of Head surface Reference System: Laboratory
Cylinder Coordinate System 1 X Axis Direction: [1.0, 0.0, 0.0] m, m, m Y Axis Direction: [0.0, 1.0, 0.0] m, m, m Z Axis Direction: X Axis Direction $\times$ Y Axis Direction Origin: [0.0, 0.0, 0.0] m, m, m Reference System: Laboratory
[injector] Coordinate System X Axis Direction, Y Axis Direction: see Calculation of X Axis and Y Axis Directions Z Axis Direction: specified Injector Direction Origin: specified Injector Origin Reference System: specified injector coordinate system (default: Cylinder Coordinate System 1)
[injector] : Nozzle [n] Coordinate System X Axis Direction, Y Axis Direction: see Calculation of X Axis and Y Axis Directions Z Axis Direction: specified Nozzle Target Origin: specified Nozzle Origin Reference System: specified nozzle coordinate system (default: Injector Coordinate System)
Cylinder Cylindrical Coordinate System Radial Axis Direction: [1.0, 0.0, 0.0] m, m, m Tangential Axis Direction: [0.0, 1.0, 0.0] m, m, m Axial Axis Direction: Radial Axis Direction $\times$ Tangential Axis Direction Origin: [0.0, 0.0, 0.0] m, m, m Reference System: Laboratory
exhaust-valve [n] Coordinate System X Axis Direction, Y Axis Direction: see Calculation of X Axis and Y Axis Directions Z Axis Direction: aligned with valve stem axis, pointing towards piston Origin: centroid of Head surface Reference System: Laboratory
Inlet [n] Coordinate System 1 X Axis Direction, Y Axis Direction: see Calculation of X Axis and Y Axis Directions Z Axis Direction: normal to Inlet [n] surface, pointing outwards Origin: centroid of Inlet [n] surface Reference System: Laboratory
intake-valve [n] Coordinate System X Axis Direction, Y Axis Direction: see Calculation of X Axis and Y Axis Directions Z Axis Direction: aligned with valve stem axis, pointing towards piston Origin: centroid of Head surface Reference System: Laboratory
Outlet [n] Coordinate System 1 X Axis Direction, Y Axis Direction: see Calculation of X Axis and Y Axis Directions Z Axis Direction: normal to Outlet [n] surface, pointing outwards Origin: centroid of Outlet [n] surface Reference System: Laboratory

Calculation of X Axis and Y Axis Directions

The X Axis Direction and the Y Axis Direction are calculated based on the given Z Axis Direction $[z_{1}, z_{2}, z_{3}]$ as follows:

INITIALIZE X Axis Direction = [1.0, 0.0, 0.0]
IF (Z Axis Direction  $\times$  X Axis Direction = 0.0){
       X Axis Direction  $: =$   $[z_{2} - z_{3}, z_{3} - z_{1}, z_{1} - z_{3}]$ 
}
Y Axis Direction  $: =$  Z Axis Direction  $\times$  X Axis Direction
X Axis Direction  $: =$  Y Axis Direction  $\times$  Z Axis Direction