Error with fix wall/region -- sphere with variable radius

Dear all,

I'm trying to use a spherical wall with a variable radius:


The 1st version gives an error that means what it says.
The variable you are using cannot be used inbetween runs
because it uses ramp(). That is a function that is only
defined when you are in the middle of a run, b/c it
means to vary the value from the start of the run to the
end. If you want to get around this, then define
your own formula that sets the radius as a function
of the timestep.

The 2nd example “works” b/c the region command
does not allow a variable for the x,y,z positions of
a sphere. So the parser is reading v_ramp as a
numeric value, and probably getting 0.0. See the
region doc page. If it doesn’t say a varialbe is
allowed for an argument, then it isn’t.


Thanks, works!

Didn’t make a mental connection that it was specific to the use of ramp()…

Best regards,