Is there an equation I can use to calculate the temperature (as a function of time) of an object which is gaining or losing heat by convection? Or equivalently, the rate of energy transfer from the object to the surrounding fluid (or vice-versa)? It can involve constants representing properties of the object and the surrounding fluid.

I know about the [heat equation](http://en.wikipedia.org/wiki/Heat_equation) for conduction and the [Stefan-Boltzmann law](http://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law) for radiation, but I can't think of one for convection.