Is there a standard class name if any of the following differential equation there similar to Laplace equation and equivalent solution based on legendre polynomial, or spherical harmonics?
$\partial^2\ u/\partial\ x^2\ +\partial^2\ u/ \partial\ y^2\ +(1/v) \partial\ u/\partial\ t\ +k\ast\ u-c=0$
v,k and c are real constants