My english is sometimes not good, so I will type from the question I need helping with.
Suppose that is the density of oxygen in the wall a < r < b of a spherical cell at time t in an animal whose heart pumps at angular frequency . Here are positive constants, and .
Find Q(t), the amount of oxygen in the cellwall at time t.
Find the most general flux vector of the form such that p and satisfy the O2 conservation equation