UDF in MDM Tutorial

mAx

Hi, I have a question about UDF. In the MDM Tutorial, the UDF calculates the piston's motion produced from the drop pressure within the valve. When I take a closer look at the UDF,I don't understand 2 stuffs. * what means F_AREA_CACHE? I understand F_AREA, but ...-CACHE? *in the CG_MOTION(), the pressure force on the piston is calculated, but I don't achieve to recognize if there is any profection for the force calculation. I mean if the piston slides on the x axis, the pressure force has to be computed along the x axis, In the UDF I don't see anything which give the choice for choosing x,y or z axis.

Any Idea Thanks mAx