Hello,

I am currently trying to simulate photolysis in an annular reactor. (H2O2+I --> 2OH).

I would like to fix a pre calculated gradient in a part of the grid. Eg. 2D case, rectangular RK: entry zone (square)- reaction zone (square)- outflow zone(square) where I is a mirrored gradient in the reaction zone. Water+H2O2 enters and is (partialy)converted to OH in the raction zone.

My understanding is that I should be able to Initialize a UDS using DEFINE_INIT, unhook the UDS from the solver and use I as a fixed source through a DEFINE_VR_RATE macro.

Question: I can't find out how to use DEFINIE_INIT on a UDS. Do I just loop over al the cells in the reaction_zone thread? is there a way to read the distance of the cell to the center of the square and write I as a function of that distance?

Sorry if I'm asking obvious stuff, and thanks for any help.

Angelo

hi,

1. For the initialization, you understanding is fairly right. loop over all the cells and set the values with C_UDS(cell_t, thrad).

2. C_CENTROID(pos, cell_t, thread) will give the coordinates of the centroid of the cell.

Thanks for the info, it helped and its working now! But I am using UDM now since UDS would only be needed to add the term to the flow.

Still gotta do some fancy footwork getting the vector calculation right

Thanks