Discussion Forum

Dear all,
I'm currently working on diffusion-reaction system using extrusion coupling variable to exchange data between 2 geometries. This model One of the extrusion coupling variable is the first derivative of dependent variable e.g., dCp/dy. The model is working well but I still want to improve its accuracy (The results depend strongly on accuracy). I'm running this model on COMSOL 3.5a.

Here information of my model and some questions.
1. Mapped meshing is used. Should I use something else?
2. PARDISO linear solver is used. (Row preordering and tolerance checking are turned off to speed up calculation time). You may have question why I turn off tolerance checking. I've tested it myself and it has no effect on the accuracy of results as long as the solution converges.
3. Symmetry is turned on.
4. I use MATLAB- COMSOL interface and activate parallel processing by the command -np 8 (I add this command in shortcut icon). Is it correct to add this command to shortcut icon or I have to add this command on my m-file?
5. I tried using linear element instead of quadratic element with much higher degree of freedom but the accuracy decreased. I also tried decreasing the tolerances(Both relative and absolute) but it can only weakly affect the accuracy.

Do you have any suggestions on how can I improve the accuracy of the model? Now I'm considering using weak constraint so COMSOL will calculate more accurate flux. Can COMSOL implement weak constraint as coupling variable? (For example, use lm1 instead of dCp/dy)