Recently, Duvall and Hanasoge ({\it Solar Phys.} {\bf 287}, 71-83, 2013)
found that large distance [Δ] separation travel-time differences from a
center to an annulus [δtoi​] implied a model of the average
supergranular cell that has a peak upflow of 240ms−1 at a depth of
2.3Mm and a corresponding peak outward horizontal flow of
700ms−1 at a depth of 1.6Mm. In the present work, this effect
is further studied by measuring and modeling center-to-quadrant travel-time
differences [δtqu​], which roughly agree with this model.
Simulations are analyzed that show that such a model flow would lead to the
expected travel-time differences. As a check for possible systematic errors,
the center-to-annulus travel-time differences [δtoi​] are found
not to vary with heliocentric angle. A consistency check finds an increase of
δtoi​ with the temporal frequency [ν] by a factor of two,
which is not predicted by the ray theory