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What's the meaning of this error information "Undefined value found" ?

Posted 2011年3月29日 GMT+8 01:49 Studies & Solvers Version 4.0, Version 4.1 2 Replies

Xiaoyi Yu
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What's the meaning of this error information below?In the error, the coordinates are the points of the grid nodes. the model is 1D. the model file has been attached.
----------
Undefined value found.
- Detail: Undefined value found in the stiffness matrix.
There are 15 equations giving NaN/Inf in the matrix rows for the variable mod1.c
at coordinates: (0), (5e-010), (1e-009), (1.5e-009), (2e-009), ...
There are 15 equations giving NaN/Inf in the matrix rows for the variable mod1.phi
at coordinates: (0), (5e-010), (1e-009), (1.5e-009), (2e-009), ...
and similarly for the degrees of freedom, NaN/Inf in the matrix columns
----------

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2 Replies Last Post 2011年12月26日 GMT+8 13:57
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2011年3月30日 GMT+8 13:34
Hi

first of all you may replace your an1(x)=1-flc2hs(x-ss,lamda2) by a step function going from 1 to 0, with offset "ss" and smoothing "lamda2/2" this is the new "pre-cooked" are the V4 way ;)

Then to get rid of the unit/orange issue on Initial values, add a phi0(x[1/m]) to make the function call unitless, for the Source term in the general form it's more complex, havent really found out, would neeed quite more time, that I do not have now

Then for me the equations are not restrained enough, you need some Direichlet or Neumann BC conditions more here, but as I'm not familiar enough with your model I'm nut sure what to put

--
Good luck
Ivar
Hi first of all you may replace your an1(x)=1-flc2hs(x-ss,lamda2) by a step function going from 1 to 0, with offset "ss" and smoothing "lamda2/2" this is the new "pre-cooked" are the V4 way ;) Then to get rid of the unit/orange issue on Initial values, add a phi0(x[1/m]) to make the function call unitless, for the Source term in the general form it's more complex, havent really found out, would neeed quite more time, that I do not have now Then for me the equations are not restrained enough, you need some Direichlet or Neumann BC conditions more here, but as I'm not familiar enough with your model I'm nut sure what to put -- Good luck Ivar
Mauricio Flores
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Posted: 1 decade ago 2011年12月26日 GMT+8 13:57
Hi! Did this problem finally get solved? I am facing the same problem on a different physical setup. This is the message I get:

"Undefined value found.
- Detail: Undefined value found in the stiffness matrix.
There are 61970 equations giving NaN/Inf in the matrix rows for the variable mod1.R1
at coordinates: (1.53872e-10,1.82966e-10,2.5563e-10), (1.61255e-10,1.78767e-10,2.58712e-10), (1.68638e-10,1.74569e-10,2.61794e-10), (1.54324e-10,1.81999e-10,2.60782e-10), (1.61733e-10,1.77834e-10,2.63944e-10), ...
There are 61970 equations giving NaN/Inf in the matrix rows for the variable mod1.R2
at coordinates: (1.53872e-10,1.82966e-10,2.5563e-10), (1.61255e-10,1.78767e-10,2.58712e-10), (1.68638e-10,1.74569e-10,2.61794e-10), (1.54324e-10,1.81999e-10,2.60782e-10), (1.61733e-10,1.77834e-10,2.63944e-10), ...
and similarly for the degrees of freedom, NaN/Inf in the matrix columns"

I am doing ALE method, setting boundary velocities on "Prescribed Mesh Velocity" as:

vx = R1t * nx,
vy = R1t * ny

and same for second boundary, where I use R2t. R1 and R2 are dependent variables to be solved for, only initial values are provided. Is this the right way to set boundary velocities? (I want radial growth of a spherical shell). If so, what goes wrong with my problem? I don't think I am missing any Boundary Conditions.

I am attaching my model, Ivar, could you help me? Or someone else?
Hi! Did this problem finally get solved? I am facing the same problem on a different physical setup. This is the message I get: "Undefined value found. - Detail: Undefined value found in the stiffness matrix. There are 61970 equations giving NaN/Inf in the matrix rows for the variable mod1.R1 at coordinates: (1.53872e-10,1.82966e-10,2.5563e-10), (1.61255e-10,1.78767e-10,2.58712e-10), (1.68638e-10,1.74569e-10,2.61794e-10), (1.54324e-10,1.81999e-10,2.60782e-10), (1.61733e-10,1.77834e-10,2.63944e-10), ... There are 61970 equations giving NaN/Inf in the matrix rows for the variable mod1.R2 at coordinates: (1.53872e-10,1.82966e-10,2.5563e-10), (1.61255e-10,1.78767e-10,2.58712e-10), (1.68638e-10,1.74569e-10,2.61794e-10), (1.54324e-10,1.81999e-10,2.60782e-10), (1.61733e-10,1.77834e-10,2.63944e-10), ... and similarly for the degrees of freedom, NaN/Inf in the matrix columns" I am doing ALE method, setting boundary velocities on "Prescribed Mesh Velocity" as: vx = R1t * nx, vy = R1t * ny and same for second boundary, where I use R2t. R1 and R2 are dependent variables to be solved for, only initial values are provided. Is this the right way to set boundary velocities? (I want radial growth of a spherical shell). If so, what goes wrong with my problem? I don't think I am missing any Boundary Conditions. I am attaching my model, Ivar, could you help me? Or someone else?

Attachments:

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