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

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9/20/2014 7:00:14 AM

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

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9/20/2014 7:53:05 AM

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.

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9/22/2014 12:45:08 PM