Question

Write the equation describing dynamics of enclosed population when its behaviour is not influenced by interactions between individuals of different age.

Answer 1

Suppose we have a region
Q = {(x, t): 0<x<l, 0<t<T}.
Let U = U(x, t) is the population of individuals of age x at time t.
Then the equation is the following:
Ux + Ut + c(x, t)U = 0.