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Hello comsol community,

I am in the process of coupling Electrostatics, Heat Transfer in Fluids, Transport of Diluted Species to Two Phase Laminar Flow (Phase Field) and having some difficulty. The simulation scenario is a water droplet evaporating on a surface under the electric field between two electrodes. I expect to see deformation of the water droplet and a water concentration profile as it evaporates. However, I was faced with this problem:

Failed to find consistent initial values. Attempt to evaluate nonintegral power of negative number. Function: ^ Failed to evaluate variable. Variable: mod1.ht.phiav, Defined as: ((1+(((mod1.ht.mua/mod1.ht.muv)^0.5)((mod1.ht.M v/mod1.ht.M a)^0.25)))^2)/(((1+(mod1.ht.M a/mod1.ht.M v))^0.5)2.8284271247461902909) Failed to evaluate variable. Variable: mod1.ht.k moist, Defined as: ((mod1.ht.Xamod1.ht.ka)/(mod1.ht.Xa+(mod1.ht.Xvmod1.ht.phiav)))+((mod1.ht.Xvmod1.ht.kv)/(mod1.ht.Xv+(mod1.ht.Xamod1.ht.phiva))) Failed to evaluate variable. Variable: mod1.ht.krr, Defined as: mod1.ht.k moist Failed to evaluate variable. Variable: mod1.ht.k effrr, Defined as: mod1.ht.krr Failed to evaluate variable. Variable: mod1.ht.res T, Defined as: ((mod1.ht.C effmod1.Tt)-(mod1.ht.k effrrmod1.Trr))-(mod1.ht.k effzzmod1.Tzz) Failed to evaluate expression. Expression: abs(mod1.ht.res T) Failed to evaluate expression. Expression: nojac(max(((((0.5abs(mod1.ht.res T))mod1.ht.xiu T)sqrt(mod1.ht.gugijgu T))/((mod1.ht.gugijgu T+((h spatial^2)sqrt(eps)))(eps+mod1.ht.C eff)))-(((mod1.ht.res T^2)mod1.ht.tauScCwd T)/(eps+((mod1.ht.C effmod1.ht.gugijgu T)/mod1.ht.gamma))),0)(1.4142135623730951455^(1-shapeorder(mod1.T)))) Failed to evaluate variable. Variable: mod1.ht.vhCwd T Failed to evaluate temporary symbolic derivative variable. Variable: mod1.ht.crosswindVDN${test8} Failed to evaluate expression. Expression: d((2mod1.ht.crosswindpir)(dvol spatial),{test8}) Failed to evaluate Jacobian of expression. Expression: (2mod1.ht.crosswindpir)*(dvol spatial) Last time step is not converged.

Why the viscosity may be negative? I don't think this problem is caused by my setting of physics model conditions, so I have tried adjusting the setting of mesh many times, but it dosen't work. Did anyone also encounter this kind of problem? How do you manage it? I hope to learn something from someone.

Best regards, Sunny PS: In the picture "model", the semicircle represents the water droplet, and the rest field represents air.