- #1
ShearStress
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Homework Statement
Prove the vector identity: [tex]\left(a\times\nabla\right)\bullet\left(u \times v\right)=\left(a \bullet u \right)\left(\nabla \bullet v \right)+\left(v \bullet \nabla \right)\left(a \bullet u \right)-\left(a \bullet v \right)\left(\nabla \bullet u \right)-\left(u \bullet\nabla\right)\left(a \bullet v \right)[/tex]
Where a, u, and v are vectors (and a is a "constant vector")
Homework Equations
N/A
The Attempt at a Solution
Okay, so in index notation I've gotten the left-hand side as...
[tex]LHS=a_{l}u^{l}\partial_{m}v^{m}-a_{m}v^{m}\partial_{l}u^{l}[/tex]
Which, since the dot product on the RHS is commutative, it seems that the RHS is just twice the LHS I've come up with in index notation. What am I missing here? Is there some weird property of the del operator in index notation that I can just double the terms?