Difference between revisions of "Gravitational Field"
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# If no Gravity command is used, the simulation will have no gravitational forces. Thus to have Earth's gravity you need a command, even if it has no parameters. | # If no <tt>Gravity</tt> command is used, the simulation will have no gravitational forces. Thus to have Earth's gravity you need a <tt>Gravity</tt> command, even if it has no parameters. | ||
Revision as of 16:07, 24 December 2013
Gravity Commands
MPM simulations can include gravity or any other constant body forces. In scripted files, the command to add gravity is:
Gravity <(gravX)>,<(gravX)>,<(gravX)>
In XML files, gravity is added with the element:
<Gravity> <BodyXForce>(gravX)</BodyXForce> <BodyYForce>(gravY)</BodyYForce> <BodyZForce>(gravZ)</BodyZForce> </Gravity>
where (gravX), (gravY), and (gravZ) are the accelerations due to gravity in the x, y, and z directions, respectively ((gravX) and (gravY) are for R and Z directions in axisymmetric calculations). In scripted files, the units are m/sec2, but in XML files, the units are mm/sec2.
In scripted files, all three parameters are optional. If all are omitted, the gravitational force field is set to Earth's gravity with down being in the negative y direction (i.e., it is equivalent to the command Gravity 0,-9.8,0). If (gravX) is included, but (gravY) and/or (gravZ) are omitted, the omitted parameters will be set to zero. In XML files, any omitted forces are set to zero.
Notes
- If no Gravity command is used, the simulation will have no gravitational forces. Thus to have Earth's gravity you need a Gravity command, even if it has no parameters.