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Time explicit pressure acoustics difficulties

Posted Sep 9, 2021, 10:16 a.m. EDT Acoustics & Vibrations Version 5.6 1 Reply

Tonni Franke Johansen
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I am trying to use the Time explicit pressure acoustics (coupled to Time explicit elastic wave) I have absorbing layers surrounding the model and get the below error message from Comsol. Anyone have a clue what Comsol want to communicate? It is difficult to identify the expression pate.imp1.g_p The boundaries are the outer boundaries of the pressure acoustics absorbing layer, where I have pate.rho*pate.c as impedance.

Undefined value found in discontinuous Galerkin formulation. -Geometry:geom1 -Boundaries:28, 30, 32, 37, 42-44 -Expression:comp1.pate.imp1.g_p

1 Reply Last Post Sep 13, 2021, 6:36 a.m. EDT
Kirill Shaposhnikov COMSOL Employee

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Posted: 3 years ago Sep 13, 2021, 6:36 a.m. EDT

Hi Tonni,

It is a typical and not at all informative error message which sometimes comes up when using time explicit solvers. What it means is that the solution has grown exponentially at some mesh element and exceeded the max double value. It can be due to a mismatch in the spatial and temporal resolution of the model, which basically means the time step was to large to obey the CFL-condition.

Unfortunately, I cannot say more without seeing you model. Could you please contact support and ask them to assign the case to me?

Best regards Kirill

Hi Tonni, It is a typical and not at all informative error message which sometimes comes up when using time explicit solvers. What it means is that the solution has grown exponentially at some mesh element and exceeded the max double value. It can be due to a mismatch in the spatial and temporal resolution of the model, which basically means the time step was to large to obey the CFL-condition. Unfortunately, I cannot say more without seeing you model. Could you please contact support and ask them to assign the case to me? Best regards Kirill

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