A gas turbine engine article includes a cooling passage network embedded in an article wall between inner and outer portions of the article wall. The network has an inlet orifice through the inner portion to receive cooling air from a cavity, a sub-passage region that includes an array of pedestals, and at least one outlet orifice through the outer portion. The array of pedestals includes first pedestals arranged in a first row and second pedestals arranged in a second, adjacent row. The first pedestals and the second pedestals define inter-row sub-passages there between. Each of the inter-row sub-passages has an inlet mouth, an outlet mouth, and a compound channel connecting the inlet mouth and the outlet mouth. The compound channel includes a first channel length over which the inter-row sub-passage has a constant cross-section and a second channel length over which the inter-row sub-passage has a non-constant cross-section.