I posted an earlier message about this. I'm having difficulty specifying the flow direction in setting up the periodic boundary conditions. I know that my flow is moving in the x direction, but when I specify a vector of (1,0,0), I get the following error:

Error: > (greater-than): invalid argument [2]: wrong type [not a number] Error Object: nanq

However, when I change the direction of the vector (for example, in the y or z direction), I don't get the error, but I know that my flow is definitely not in the y or z directions. So now I don't know if I can trust my results.

Any thoughts? Thanks.

which is the periodic direction?i think periodicity is indipendent of the flow direction..