We're calculating pressure and velocity incorrectly in the Warp backend.

[mehdiataei]

Since we're using the pull method, a must apply one streaming step (plus, apply_bc poststreaming) before calculating rho and u.

[hsalehipour]

that's not quite right. The zero'th and first moment of the Collision operation is zero actually and so the only issue we have with the way we are outputting rho and vel is at the boundaries and so all we need to be cautious of is not to include boundary voxels in our viz and analysis unless it is needed in our analysis.