Discussion Forum

Hello I am solving a 2D transient Poisson and Nernst-Planck equations on two domains. The initial conditions are different in two domains. In the Poisson equations (There are 2 Poisson equations), on the right hand side I have a constant (epsilon) which is defined in Parameters. This is a small constant (Please see the attached photos) I can solve the problem when it is equal 8.85 * (10^(-8)) but the correct value of this constant is : 8.85 * (10^(-10)) . When I use this value the problem does not converge and I get this error: comsol Repeated error test failures. May have reached a singularity I am using PARDISO solver and I also changed the solver setting as recommended in this link : www.comsol.com/support/knowledgebase/1172/ I also decreased the relative tolerance in different steps but none of these tricks was helpful. I am pretty sure there should be a way to solve this problem for epsilon = 8.85 * (10^(-10)) The thing is I can not change the value of initial or boundary conditions or any constants in my model. For example if I multiply the initial conditions by 0.001 this problem converges perfectly but I do not want to change my initial conditions.** I was hoping if using a preconditioner or changing the solver or mesh or WHATEVER could resolve my issue. ** I would really appreciate your time taking a look at my model and help me get around this problem. The file of my model and two screenshots are attached. Thanks in advance for your support.