Hi, 

I`m trying to solve the 1D advection-diffusion-reaction equation dc/dt+u*dc/dx=D*dc2/dx2-kC using Fortan code but I`m still facing some issues. first I solved the advection-diffusion equation without including the source term (reaction) and it works fine. but when including the source term (decay of substence with the fisr order decay -kC)I could not get a correct solution. I have read that I need to use the spliting time mthod or as called also the operator time method, but I do not know how to apply it.
Could any one help to provide a simple code for solving this advection-diffusion-reaction equation ? I would appriciate your help.

Regards,

Kader

kader <fabdelkader@pi.ac.ae> wrote in message <qJWdnbs5kcHhfIHJnZ2dnUU7-a-dnZ2d@giganews.com>...
> Hi, 
> 
> I`m trying to solve the 1D advection-diffusion-reaction equation dc/dt+u*dc/dx=D*dc2/dx2-kC using Fortan code but I`m still facing some issues. first I solved the advection-diffusion equation without including the source term (reaction) and it works fine. but when including the source term (decay of substence with the fisr order decay -kC)I could not get a correct solution. I have read that I need to use the spliting time mthod or as called also the operator time method, but I do not know how to apply it.
> Could any one help to provide a simple code for solving this advection-diffusion-reaction equation ? I would appriciate your help.

Try to implement this term kC in time-implicit scheme; i.e. put it in t_(n+1) when solving in (t_n , t_(n+1) ). This scheme is more stable.

Bruno

You might try to use time-implicit scheme for this term, which is stable and void numerical oscillation.

kader <fabdelkader@pi.ac.ae> wrote in message <qJWdnbs5kcHhfIHJnZ2dnUU7-a-dnZ2d@giganews.com>...
> Hi, 
> 
> I`m trying to solve the 1D advection-diffusion-reaction equation dc/dt+u*dc/dx=D*dc2/dx2-kC using Fortan code but I`m still facing some issues. first I solved the advection-diffusion equation without including the source term (reaction) and it works fine. but when including the source term (decay of substence with the fisr order decay -kC)I could not get a correct solution. I have read that I need to use the spliting time mthod or as called also the operator time method, but I do not know how to apply it.
> Could any one help to provide a simple code for solving this advection-diffusion-reaction equation ? I would appriciate your help.
> 
> Regards,
> 
> Kader
> 

Try MATLAB's "pdepe" (at least to check your results) - it uses an implicit method for time integration.

Best wishes
Torsten.