The advection–diffusion equation is used to compute the distribution of concentration along the length of a rectangular chemical reactor: ∂c ∂t = D ∂ 2 c ∂x2 − U ∂c ∂x − kc , (1) where c = concentration (mg/m3 ), t = time (min), D = a diffusion coefficient (m2/min), x = distance along the tank’s longitudinal axis (m) where x = 0 at the tank’s inlet, U = velocity in the x direction (m/min), and k = a reaction rate (min−1 ) whereby the chemical decays to another form. Develop an explicit scheme to solve this equation numerically. Test it for k = 0.15, D = 100, and U = 1 for a tank of length 10 m. Use a ∆x = 0.5 m, and a step size ∆t = 0.001 min. Assume that the inflow concentration is 100, at the outlet the concentration is not changing with x position, and that the initial concentration in the tank is zero. Perform the simulation from t = 0 to 100 min and plot the final resulting concentrations versus x.