Velocity-space divergence
= Velocity-space divergence
{title2=$\nabla_{\mathbf v}\cdot\mathbf A$}
The <divergence> with respect to <velocity> coordinates, with position held fixed. In $d$ <dimensions>, $\mathbf A(\mathbf x,\mathbf v)=\mathbf B(\mathbf x)-a(\mathbf x)\mathbf v$ has $\nabla_{\mathbf v}\cdot\mathbf A=-da$. A kinetic conservation law must retain this term for velocity-dependent forces.