Hi Luca
My understanding (and use) if the [1/..] is to ensure correct units, and to cancel out unwanted unit dimensions, as you pointed out. If "t" is defined in [min] then t[min]*[1/sec] => t*60[1] (without units) and that is what I would use within a sinus function.
That COMSOL flags something red in V3.5 does not necesarily mean an error, neither than it will calculate wrongly, it's just a warning of possble incoherence in units. Among other integration coupling constants do not have their units following them correctly, I expect this to be better in the new V4, coming soon.
Now back to your second calculation of rotation, if you are in 2D (I assume so) normally "s" is defined internally, s is going from 0-1 along an adge, but the direction is not obvious, check the edge "arrow" in edge view. You might have nameing conflict there, s has no unit =[1] , I would call your sinus function something else perhaps "si".
Finally your expression "*(30[cm]-y[cm])/(30)" is this "*(1-y/(30[cm]))" you mean ?, which for me is dimensionless but different to the first expression (I assume "y" is a length related someway to [m] this might be wrong, see below).
The easiest way to check I know about, is to set up, in 2D structural, a rectangular geometry block of 1[m] side, ands olve as is, all defaults.
Then postprocess on an edge and type "y", "y[cm]" and finally "y[1/cm]", check the value and the dimensions of the reply.
Mostly you will find the replies within COMSOL, and one must first "isolate" the issues to something unambiguous and simple.
So I assume there might be a few items that could explain the "red" flag of COMSOL
Good luck
Ivar
My understanding (and use) if the [1/..] is to ensure correct units, and to cancel out unwanted unit dimensions, as you pointed out. If "t" is defined in [min] then t[min]*[1/sec] => t*60[1] (without units) and that is what I would use within a sinus function.
That COMSOL flags something red in V3.5 does not necesarily mean an error, neither than it will calculate wrongly, it's just a warning of possble incoherence in units. Among other integration coupling constants do not have their units following them correctly, I expect this to be better in the new V4, coming soon.
Now back to your second calculation of rotation, if you are in 2D (I assume so) normally "s" is defined internally, s is going from 0-1 along an adge, but the direction is not obvious, check the edge "arrow" in edge view. You might have nameing conflict there, s has no unit =[1] , I would call your sinus function something else perhaps "si".
Finally your expression "*(30[cm]-y[cm])/(30)" is this "*(1-y/(30[cm]))" you mean ?, which for me is dimensionless but different to the first expression (I assume "y" is a length related someway to [m] this might be wrong, see below).
The easiest way to check I know about, is to set up, in 2D structural, a rectangular geometry block of 1[m] side, ands olve as is, all defaults.
Then postprocess on an edge and type "y", "y[cm]" and finally "y[1/cm]", check the value and the dimensions of the reply.
Mostly you will find the replies within COMSOL, and one must first "isolate" the issues to something unambiguous and simple.
So I assume there might be a few items that could explain the "red" flag of COMSOL
Good luck
Ivar
