# Solve a system of 2nd order PDE with Mathematica

Posted 4 months ago
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 Hi community,I'm working on a drift-diffusion model which gives equations of the following type:(a[0, 1] ' ' )[z] + 5.78 a[0, 1] [z] - 0.036 (a[0, 1] ' )[z] + (UnitStep[-1.63265 + z] - UnitStep[1.63265 + z]) == 0wher a[ i , j ][z] are the expressions of interest (here as an example for i=0, j=1).The most simple system of equations for a[0,1], a[1,1], a[1,2], a[2,2] can be found in the notebook.The boundary condition should be n vanishes in both directions (it is a density).I was trying NSolve, but unfortunately I only get oscillating results.Is it possible that Mathematica has a problem with this type of DGL? I don't get any meaningful results for uncoupled equations either. What can I do ?Best regards,Michael&Wolfram Notebook
 Welcome to Wolfram Community! Please make sure you know the rules: https://wolfr.am/READ-1STYour post is too vague. Please EDIT your post and describe your subject extensively providing your code. You can format your code like that int = Integrate[1/(x^3 - 1), x]; Map[Framed, int, Infinity] You can also embed notebook or attach notebook.