Discussion Forum

Hello comsol community,

I am a bit struggling on this error message. I am relatively new to COMSOL. So not quite familiar with what went wrong. Any sort of comments and guidance will be much appreciated. I see the following error

"Feature: Stationary Solver 1 (sol1/s1) Attempt to evaluate nonintegral power of negative number. - Function: ^ Failed to evaluate variable. - Variable: comp1.i_0 - Defined as: (((k0F)(comp1.C_l_r^aA_ca))((C_s_max-comp1.C_s1)^aA_ca))(comp1.C_s1^aC_ca) Failed to evaluate variable. - Variable: comp1.i_n - Defined as: (comp1.i_0(exp(((FaA_ca)comp1.eta_act)/(RT))-exp((comp1.eta_act(F(-aC_ca)))/(RT))))/(unit_m_cf^2) Failed to evaluate expression. - Expression: comp1.i_n Failed to evaluate operator. - Operator: comp1.linext1 - Geometry: geom2 - Boundaries: 3, 6 Failed to evaluate expression. - Expression: comp1.linext1(comp1.i_n) Failed to evaluate expression. - Expression: d((-comp1.linext1(comp1.i_n)test(comp2.C_s)/F)(dvol_spatial),{test@1}) Failed to evaluate Jacobian of expression. - Expression: (-comp1.linext1(comp1.i_n)test(comp2.C_s)/F)*(dvol_spatial)"

I would like to focus on the first part which is - Attempt to evaluate nonintegral power of negative number. - Function: ^ Failed to evaluate variable.

Can someone please explain what is going on here ? Please let me know if the forum needs further info. Many thanks !