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On how to initialize a UDS

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Old   November 12, 2003, 21:14
Default On how to initialize a UDS
Angelo Sozzi
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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.

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Old   November 14, 2003, 13:58
Default Re: On how to initialize a UDS
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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.

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Old   November 19, 2003, 17:31
Default Re: On how to initialize a UDS
Angelo Sozzi
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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

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