Briefly explain what is dispersion and how is it different f

Briefly explain what is dispersion, and how is it different from diffusion alone? In your answer comment on the relative sizes of the diffusion coefficient and the dispersion coefficient. The dispersion equation is: partialderivative c/partialderivative t = E partialderivative^2 c/partialderivative x^2 Define all of the symbols in this equation. Demonstrate that the equation, c = A/Squareroot t exp (-x^2/4 Et) is a solution to the dispersion equation, where A is a constant. For the expression given in (c), write down the expression that corresponds to the maximum value of c with distance. The investigation of a river that had been inadvertently polluted by the spillage of toxic, bromobenzene-containing waste revealed that the bromobenzene concentration 2 km downstream had a maximum value of 800 mg L^-1. A concentration 50 m from this maximum of 401 mg L^-1. The stream flows at 0.4 km h^-1. Use these data to estimate a value of the dispersion coefficient of bromobenzene, and comment on the size of the dispersion coefficient in the light of your knowledge of typical diffusion coefficients.

Solution

Dispersion can be differentiated from diffusion that it is caused by non ideal flow parameters and occurs at a macroscopic level but diffusion occurs at molecular level.(Brownian motion).