[sajad_abasi]

hi.
i have a porous domain in my simulation.i want to change the porous resistance in each time step by value of the porous resistance in previus time step minus a sumation.i mean that if cvr is porous ressis so i want this:
cvr=cvr-sumation.
i deffined an additional variable by name of cvr and i use Update Loop = TRANS_LOOP to keep previous value of cvr.i set "cvr=20000[m^-1]" and in porous domain i set the "resistance loss coefficient" to be "cvr".i run it and it works well.after that when i set "cvr=cvr" in domain the software can not read previous value and can not recognize the variable "cvr" and set the resistance of porous to be zero but cvr has the value of 20000 from last time step.
im really confused.
best regards.