Formulating Field function with cell index
 

Dear all,

I am trying to formulate a source term for the 2-D transport equation, which is a function of the passive scalar value in the cell and the cell above it. Is there a way to address the cells by the index?

e.g. ${Passive Scalar}(i)*div($$Velocity(i)*$Volume(i)-${Passive Scalar}(i+1)*div($$Velocity(i+1)*$Volume(i+1)



Thank you very much in advance!