Add the constant pressure gradient to the momentum equation
 

Hello, everybody,
I want to add a constant pressure gradient to the momentum equation, say, 7.915e-3, and I use the icoFoam to transform my own solver. I saw the solution in this forum, imitating in the channelFoam, but when I run it, It appear the following errors:
Attachment 34219
and the added part in the .C file is following:
Attachment 34222
and the transportProperties file is following:
Attachment 34221
and the gradP file is following:
Attachment 34220
I really don't know how to do, someone can help me? thank you very much!