The resistance of a diode changes with the voltage across it which is called dynamic resistance. If the voltage across the diode is constant we can find the dynamic resistance from the slope of the I-V curve. So for small variations we can use that dynamic resistance value in the diode model.
But if the voltage across the diode varies a lot like in a AC to DC rectifying diode, I guess we cannot just model a diode’s dynamic resistance with a constant series resistance. If we want to formulate the diode current in such case how is the diode dynamic resistance modeled? Here aren’t we facing a non-linear resistor?