- #1

- 73

- 2

I am having trouble understanding why T

^{ij}can be non-zero for i≠j. T

^{ij}is the flux of the i-th component of momentum across a surface of constant x

^{j}. Isn't the i-th component of momentum

**tangent**to the surface of constant x

^{j}and therefore its flux across that surface zero? What am I missing here?