CONSTRUCT COORDSYS SPHERICAL

        

This command is used to define a local spherical coordinate system.

FEMGEN command

CONSTRUCT COORDSYS SPHERICAL [csyst] Pnamo Pnamz Pnamx

csyst = optional name of the local coordinate system

Pnamo = origin of coordinate system

Pnamz = defines the local z-axis direction, `pnamo' to `pnamz'

Pnamx = defines the local x-axis direction, which is the vector from `pnamo' to `pnamx' projected onto the plane normal to the local z-axis.

The spherical coordinates $(r, \phi, \theta )$ are connected to the local (x,y,z) coordinates by $x=r*cos(\theta )*sin(\phi )$, $y=r*sin(\theta )*sin(\phi )$ and $z=r*cos(\phi )$ where $\theta$ and $\phi$ are in degrees.

Local spherical coordinate systems may be selected for use in the definition of point coordinates (in terms of the local spherical coordinates $r, \phi ,$ and $\theta )$ using the command CONSTRUCT COORDSYS LOCAL, or for the creation of skew boundary conditions using the command PROPERTY ATTACH

 

Figure 2.3: Definition of a spherical coordinate system

Notes:

1.

Default names
If no name is entered a default name is created, this is CSn where n is a count of defined coordinate systems. The default name can be changed with the CONSTRUCT NAME command.

Examples:

1.

CONSTRUCT COORDSYS SPHERICAL CS1 P1 P2 P3

This creates a spherical coordinate system called CS1 with its origin at P1. The z-axis is defined by P2 and the x-axis by P3

See also the following commands

'CONSTRUCT COORDSYS LOCAL'
'CONSTRUCT NAME'
'PROPERTY ATTACH'
'UTILITY TABULATE GEOMETRY CSYST'
'UTILITY DELETE GEOMETRY CSYST'

FEMVIEW command

 

CONSTRUCT COORDSYS SPHERICAL [csyst] def

This command is used to define a local spherical system for use with RESULTS TRANSFORM LOCAL

csyst = optional name of the local coordinate system

defn = two sets of model coordinates (x, y, z) defining the local origin and local axis of the system. OR

= the keyword NODES with two node numbers defining the local origin and local axis of the system. OR

= X or Y or Z if the local axis of the sphere is one of the global axes.

Each time that a new axis system is created an axis set is drawn at the local origin to indicate the location and orientation of the coordinate system.

When the resulting spherical system is used with RESULTS LOCAL TRANSFORM the radial (or local x) direction is normal to the surface of the sphere, the hoop (or local y) direction is in a plane normal to the axis and the local z direction is perpendicular to these two.

See also the following commands

'RESULTS TRANSFORM LOCAL'
'UTILITY TABULATE '

Examples:

1.

CONSTRUCT COORDSYS SPHERICAL 1.1 1.2 2.1 3.2 2.1 4

Creates a cylindrical axis system with the origin at x=1.1, y=1.2 and z=2.1. The local axis of the system passes through x=3.2, y=2.1 and z=4. A name for the system will be generated automatically.

2.

CONSTRUCT COORDSYS SPHERICAL SPH11 NODES 1 10

Creates a cylindrical axis system called SPH11 with the origin at node 1, the local axis defined by node 10.