May be you can use quotient rule
This is a rather basic one sorry, but I am rather stuck.... all I want to do is apply the chain rule to combine the advective transport equation for two solutes such that and
where Ca is the concentration of 'a' in the fluid, D is a dispersion coefficient, v is velocity and Ja is the flux of 'a' to the fluid etc
to get can anyone please help?
I think I might be getting there....
Taking the one dimensonal case(s) (same for C2)
and using the product rule as a special case of the chain rule
and rearranging for dr/dt in terms of C_1
Substituting (1) for C_1 and C_2 into (4) i get;
All I need to do is expand this and rearrange but I am total stuck has how to expand out the brackers, as I suck at math. Can anyone enlighten me? Please. I would be really really grateful.