====== Tutorial 7 - Adding Diffusion to the Transport Model ====== ===== 5/5 ===== \\ **Creating the model structure** - Open the second model again. - Connect //Begin// and //End// with a [[Transfer|Transfer]] block. Name the block “Diffusion_Down”. - Connect //End// and //Begin// with a [[Transfer|Transfer]] block. Name the block “Diffusion_Up”. - Connect //End// and //Out// with a [[Transfer|Transfer]] block. Name the block “Diffusion_Out”. \\ {{tutorial_7_7.png?600}} \\ **Assigning values**

Edit //Diffusion_Down//. Enter the same expression “D/(R * dx²)”, where //D// has the same properties as in the previous model:

\\
^**Name**^**Type** ^**Unit** ^**Full Name** ^**Value/Expression**^ |D |Parameter|m² year^-1|Diffusion coefficient|1 |
\\
Assign the same expression to //Diffusion_Up// and //Diffusion_Out//.
[[Running_simulations|Run a simulation]] and make a plot of //Flux_Out//. Do you get the same result as in the [[Compartment|Compartment]] model?
[[Running_simulations|Run simulations]] with different values for //N//. How many discretizations are needed to make the curve converge?
Change the Advection Velocity //v// to 10 m year^-1. As the total depth of the media is 10m, the [[transport|transport]] should now occur in a much shorter time span than before. Change the end time of the simulation to a lower value, say 3 years.\\ \\ How many discretizations are now needed to make the curve converge?

\\ \\ **Solution to the excersise** * {{solution_transport_4.eco}} **Previous** * [[Tutorial_7-Adding_diffusion_to_the_compartment_model|Adding diffusion to the compartment model (4/5)]] **Reference** * [[Tutorials|Back to Tutorials]] * [[start|Home]]